VERIFIABILITY, RELIABILITY, AND NATIONAL SECURITY

Abstract

The rejection of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) by the U.S. Senate in October 1999 could have been avoided, and the consequences of that vote still loom in the minds of supporters of the treaty. President Barack Obama has embraced the vision of a world free of nuclear weapons, and a key element of the Obama administration's arms control agenda is delivering on U.S. CTBT ratification. In order to secure the two-thirds majority in the Senate necessary to ratify the treaty, senators that remain skeptical of nuclear disarmament must also be convinced that the entry into force of the CTBT is in the national security interest of the United States. This article provides an analysis of the issues surrounding U.S. CTBT ratification divided into three segments—verifiability of the treaty, reliability of the U.S. stockpile, and the treaty's impact on U.S. national security—and concludes that CTBT ratification serves the security objectives of the United States. The CTBT constitutes an integral component of the multilateral nonproliferation architecture designed to prevent the proliferation of nuclear weapons, and it constrains the qualitative development of nuclear weapons, thereby hindering efforts by states of concern to develop advanced nuclear weapons.

Keywords:

• Comprehensive Nuclear-Test-Ban Treaty
• nuclear weapons
• nuclear testing
• verification
• United States
• Treaty on the Non-Proliferation of Nuclear Weapons

With more than 180 signatory states and nearly 150 ratifying states, it has become increasingly apparent that the Comprehensive Nuclear-Test-Ban Treaty (CTBT) enjoys near-universal support. This point is further illustrated by a UN General Assembly resolution in October 2008 that called for the CTBT's early entry into force; it was adopted with a resounding 175 votes in favor, just three abstentions (India, Mauritius, and Syria), and only the United States voting against it.1 Nonetheless, the fate of the CTBT is far from certain. The provisions of the treaty stipulate that all forty-four “Annex 2 states”—states that participated in CTBT negotiations at the Conference on Disarmament from 1994 to 1996 and possessed nuclear reactors at that time—must ratify the treaty before it enters into force. There are nine Annex 2 states that must still ratify the CTBT; six of them have already signed the treaty (China, Egypt, Indonesia, Iran, Israel, and the United States), and three have not (India, North Korea, and Pakistan). If there is to be movement toward CTBT entry into force, U.S. ratification is essential. In order to understand the significance of a potential U.S. CTBT ratification, one must recognize the role that the United States played in the treaty's negotiations. In an interview with the Preparatory Commission for the CTBT Organization (CTBTO), Ambassador Jaap Ramaker, who chaired the final round of CTBT negotiations, asserted, “We would never have had a Treaty had the [United States] not been so actively supportive” of commencing treaty negotiations.2 In the same vein, U.S. leadership is now pivotal to securing CTBT entry into force.

The political environment during the Senate's initial consideration of the treaty was extremely volatile, further complicating an already polarized debate over a particularly sensitive U.S. interest—nuclear weapons in U.S. national security. Although much has changed in the interim, the probable upcoming debate in the Senate will likely revolve around the same concerns voiced by opponents of the treaty in 1999. In October 2007, Senator Carl Levin (Democrat of Michigan) included a provision in the fiscal 2008 Defense Authorization Act expressing a sense of the Congress that the CTBT should be ratified. In response, Senator Jon Kyl (Republican of Arizona) criticized the move and, with the support of thirty-six other Republican senators, drafted a letter to Senator Levin questioning how he could express a favorable sense of the Congress toward a treaty that was rejected by the Senate and that had received no further debate or consideration.3 On the Senate floor, Senator Kyl expounded on his aversion to the treaty, which rested on three basic concepts: verifiability of the CTBT, reliability of the U.S. stockpile, and the treaty's contribution to U.S. national security and nonproliferation objectives.4 This article discusses the merits of the CTBT vis-à-vis the U.S. national security interest and argues that U.S. ratification would not only bolster the international nonproliferation regime and improve the U.S. image abroad, but also provide substantive security benefits to the United States.

Verifiability

During the Senate debate on the CTBT in 1999, opponents of the treaty argued that the test ban would not be effectively verifiable and would in fact allow other states to clandestinely develop and test nuclear weapons while the United States remained bound to the provisions of the treaty. These arguments focused on the possibility that states could evasively test nuclear weapons underground, primarily through the process of cavity decoupling, and thus avoid detection. Notably, this issue first emerged between 1958 and 1960, during nuclear test ban talks between the Soviet Union, the United Kingdom, and the United States—the nuclear powers at the time. At U.S. physicist Edward Teller's request, physicist Albert Latter performed a series of theoretical computations in order to predict the limitations of monitoring nuclear tests conducted in large underground cavities. Based on Latter's “tentative findings,” detecting a nuclear test conducted in this manner would be significantly more difficult than detecting a non-evasive test; subsequently, President Dwight Eisenhower further embraced the proposal for a test ban that would exclude underground testing, which eventually led to the 1963 Limited Test-Ban-Treaty.5

In order to assess the net benefit to the United States of a given arms control treaty or measure, baselines for effective verification must be established. Effective verification was defined by Ambassador Paul Nitze during the Senate's consideration of the Intermediate-Range Nuclear Forces Treaty in 1988 as retaining the capability to detect any militarily significant violations of the treaty's provisions in sufficient time to act and deny the violator the benefit of cheating. While the Senate considered ratification of START in 1991, James Baker added that effective verification should allow for the detection of marginal violations “that do not present immediate risk to U.S. security.”6 The issue of military significance is fundamental in establishing a baseline for effective verification. If a state of concern were to conduct a militarily significant nuclear test, or a series of tests, that could eventually lead to militarily significant advances in weapons design or performance, U.S. national security would be adversely affected. In other words, the verification mechanism of the CTBT must reliably detect nuclear explosions that would upset the strategic balance between the United States and other nuclear-capable states, as well as serve U.S. security interests in the pursuit of nuclear nonproliferation.

Status of the International Monitoring System

The CTBTO relies on four verification technologies to monitor the globe for evidence of nuclear test explosions: seismic, hydroacoustic, infrasound, and radionuclide. The verification mechanism of the CTBTO, the International Monitoring System (IMS), comprises stations placed strategically around the world that employ these technologies to ensure compliance with the treaty. Once completed, the IMS will consist of 321 monitoring stations and sixteen radionuclide laboratories situated in about ninety countries throughout the world.7 As of June 2009, more than 245 IMS facilities had been fully certified, while another fifty-seven stations were in the construction or testing phase. An additional thirty-three stations in the IMS network remain in the planning stage.8 All five nuclear weapon states (NWS) now host IMS stations that transmit data to the CTBTO International Data Centre (IDC) through a global communications infrastructure. Even with less than 60 percent of IMS stations transmitting data to the IDC in Vienna, more than twenty IMS stations picked up signs of the nuclear test conducted by the Democratic People's Republic of Korea (DPRK) on October 9, 2006.9 In addition, eleven non-IMS seismic stations in Asia, Australia, Europe, and North America promptly detected and identified the event.10 Waveform data collected from these stations enabled the CTBTO to determine the event's time and location. However, in order to prove that the event was of a nuclear origin, air samples were needed to identify the existence of relevant radionuclides or noble gases.11

If a nuclear test is conducted underground in a sufficiently contained manner, particulate radionuclides are not expected to be released into the atmosphere. However, noble gases generated by the nuclear explosion can escape from the underground test site, which is why forty IMS stations will be equipped with noble gas-detection capabilities. Although this technology was experimental in nature when the regime was envisioned, half of the planned stations are currently operational. Moreover, the twenty noble gas stations that currently operate double the ten stations that were in operation at the time of the 2006 DPRK test that had accurately identified the test's nuclear origin.

The October 2006 DPRK nuclear test provided the CTBTO with an opportunity to evaluate the IMS and its ability to detect suspected nuclear detonations. Using Atmospheric Transport Modeling (ATM) technology, IMS staff members predicted that the Yellowknife noble gas station in Canada would detect the noble gas xenon-133 (Xe-133) between October 22 and October 27, 2006. As the ATM data indicated, the Yellowknife station registered levels of Xe-133 consistent with an approximately 1-kiloton (kt) nuclear explosion on the Korean Peninsula on October 9, 2006.12

The development of the IMS radionuclide network has provided real impetus for the greater scientific community in terms of expanding understanding of radionuclide technology, which in turn enhances its contribution to CTBTO monitoring capabilities. In addition, “Deployment of additional atmospheric-gas and aerosol stations for academic research, and further analysis and modeling of the measurements could greatly expand current capabilities,” as Raymond Jeanloz reported.13 With regard to infrasound technology, though the monitoring capacity of infrasound stations is less developed than that of the IMS seismic stations, a result of the construction of the IMS infrasound network is that a community of scientists and technicians are quickly gaining experience in this field. For example, infrasound stations have documented debris from comets and meteorites impacting Earth's atmosphere and have monitored natural events such as volcanic eruptions. This has resulted in an increased capacity to employ infrasound technology to determine the location and size of explosions.14 Hydroacoustic stations, which monitor for underwater explosions, compensate for areas in southern oceans where the sensitivities of the IMS seismic network are weakest, while seismic stations can offer coverage in northern oceans where the hydroacoustic network is weak.15

In the case of an ambiguous seismic event, states parties may request an on-site inspection (OSI) in order to determine whether a violation of the CTBT has occurred. OSIs constitute the most intrusive element of the treaty's verification mechanism and can only be requested after the CTBT has entered into force. In order to assess the preparedness of the OSI element of the CTBT verification regime, in September 2008 the Preparatory Commission ran its first ever integrated field exercise (IFE) for on-site inspections at the former Soviet testing facility in Semipalatinsk, Kazakhstan. The exercise, which took place over one week in Vienna and one month of field activities in Kazakhstan, supported the objectives of the CTBTO by “testing, evaluating and integrating OSI elements such as the test manual, equipment, standard operating procedures and infrastructure.”16 The IFE was described by Tibor Tóth, executive secretary of the CTBTO, as “probably the most challenging scenario, from different angles.” Oliver Meier, a researcher with the Institute for Peace Research and Security Policy who observed the exercise, noted that, “Although there was some disagreement about the scenario, it was generally acknowledged that the inspectors performed well under difficult conditions.”17

National Technical Means

There have been significant improvements since the Senate debate in 1999 in not only the area of coverage provided for by the IMS and enhancements in the monitoring technology, but also the capacity for national technical means (NTM) to monitor for nuclear explosions. One example of this growth is the worldwide expansion of broadband digital seismometers. Although only a small portion of these seismometers will constitute IMS seismic stations, in the case of an ambiguous event, states parties may utilize NTM sources to strengthen the case for an on-site inspection.18

Several cases illustrate the overall sensitivity of the IMS seismic network when linked with NTM. At the time of the 2000 Kursk submarine disaster, “a small blast—estimated at less than 20 kilograms yield” was detected by IMS and other seismic stations as far away as 5,000 kilometers (km) before the main explosions aboard the Russian submarine.19 This level of detection represents a significant improvement from a decade ago. During the Indian and Pakistani nuclear tests in 1998, a seismic threshold of less than 10–20 tons was established from non-IMS seismic stations.20 Though the yield of the 2006 DPRK nuclear test is generally believed to be between 500 and 700 tons, seismic data recorded from underground chemical explosions reveal that yields as low as 2 tons would have been detected in some areas of the Korean Peninsula. 21Though IMS stations and NTM cannot provide for this threshold globally, these examples demonstrate that detecting seismic events is possible at yields significantly smaller than originally anticipated. During CTBT negotiations, a 1 kt yield was accepted as a baseline criterion for designing a “cost-effective system,” though it became apparent that IMS capabilities allowed for monitoring well below this nominal level.22

The complementary role of NTM in supporting the objectives of the IMS is fundamental in understanding verification issues related to the CTBT, and these modalities will continue to enhance the detection capabilities of the CTBTO. Furthermore, technological progress will continue to augment the detection capability of the CTBTO in ways unforeseen by the drafters of the treaty. For instance, the recent discovery that analysis of ambient background noise recorded on seismometers can produce images of horizontal variations in seismic wave velocities throughout Earth's crust will allow for the detection of small or decoupled tests at regional distances by quantifying seismic recordings of explosions.23

Additional Monitoring Technologies

Interferometric synthetic aperture radar (InSAR) is another recently explored monitoring technology used by the United States in its Lacrosse satellite program. The InSAR method utilizes radar images from satellites that reveal line-of-sight displacements in Earth's surface and can be used to monitor for clandestine nuclear test explosions.24 The European Space Agency, Japan, and Canada have also developed InSAR technology, which measures the subsidence of the earth following a disruption, within a few millimeters of accuracy in some cases. InSAR interferograms can allow scientists to pinpoint the location of a seismic event to within 100 meters, as well as to distinguish between earthquakes and nuclear test explosions based on subsidence patterns.25 Studies conducted by the Lawrence Livermore National Laboratory (LLNL) at the Nevada Test Site indicate that InSAR data could be utilized to detect surface deformations caused by nuclear tests at depths of 600 meters, regardless of whether the nuclear test resulted in the formation of a surface crater. The technology also has the potential to detect underground facilities, such as tunnels or cavities that could be utilized for nuclear testing preparations.26 Although it is unclear whether this technology will be effective in all regions, experience at the Nevada Test Site indicates that InSAR would be well suited for arid regions, especially areas of interest in the Middle East.27

Critics of the CTBT argue that InSAR technology has several limitations, including the need to maintain accurate InSAR databases, and cite the absence of observable subsidence after the DPRK's nuclear test in October 2006.28 However, satellite imagery from more than twenty years ago revealed surface scarring around the actual test site and support sites, indicating that the DPRK had selected this test site at a much earlier date. The absence of observable “mining equipment, ore concentration processing facilities and large tailings piles” was a key indicator that the facility was constructed as a nuclear testing tunnel.29 Moreover, commercially available high-resolution satellite imagery has provided governments, as well as nonproliferation specialists, with an additional means with which to monitor compliance with arms control agreements. For example, David Albright and Paul Brannan of the Institute for Science and International Security identified suspected North Korean testing facilities to within a few square kilometers with commercially available high-resolution satellite images.30 Another area where satellite imagery can play a significant role is in the identification of nuclear weapons testing preparations, which can trigger special attention by IMS and non-IMS sensors.31 As satellite imaging and InSAR technology continue to evolve, additional layers of capability will further complicate potential evasion scenarios, illustrating the complementary nature of NTM to the CTBT monitoring system.

Evasion Scenarios

Opponents of the CTBT, including former Bush administration officials, have acknowledged that the United States would benefit from monitoring stations situated in strategically important locations to detect and deter violations of the treaty. There are sensitive regions, such as in Russia and China, which are currently inaccessible to U.S. monitoring systems.32 Furthermore, the 2002 National Academy of Sciences (NAS) study on monitoring a nuclear test ban stated, “The capabilities to detect and identify nuclear explosions without special efforts at evasion are considerably better than the ‘one-kiloton worldwide’ characterization that has often been stated for the IMS.”33 According to Daryl Kimball, executive director of the Arms Control Association, “When national technical means and civilian seismic networks, plus the option of on-site inspections are taken into account, no would be cheater could confidently conduct a nuclear weapon test explosion underground, underwater, or in the atmosphere without a very high risk of detection.” 34 Moreover, conducting a nuclear test explosion in an evasive manner would complicate attempts to gather scientific knowledge from the test, because the test would be oriented more toward evasion than data acquisition.

Although the 2002 NAS report on technical issues surrounding the CTBT explored many potential ways an actor might employ evasion techniques to escape detection, including testing shortly after a large-scale earthquake, the report concluded that cavity decoupling and mine masking were the most serious options that required thorough examination. The concept of mine masking involves the detonation of a large quantity of chemical explosives in an active mining area to conceal the seismic signal of an explosive nuclear test. Chemical explosions used in mining projects are typically ripple-fired—detonated in a series of blasts instead of all at once—and therefore inefficient at generating seismic signals that could mask a nuclear explosion. The NAS committee concluded that in an evasion scenario of this type, the nuclear yield could not exceed approximately 10 percent of the chemical explosive yield. For this reason, the potential violator must use a single-fired chemical explosion in any masking attempt. Due to the rarity of such events, any large single-fired chemical explosion would likely attract suspicion, especially given the capabilities of the IMS and NTM seismic networks, which have increased significantly since the publication of the NAS report.35 Moreover, anticipating this possible evasion scenario, treaty negotiators included confidence-building measures whereby states parties would voluntarily notify the Technical Secretariat of any chemical mining explosions with yields of 300 tons or greater within their territories.36

In a decoupled explosion, almost all of the energy released by a nuclear test in a sufficiently expansive underground cavity is exhausted in the creation of high gas pressure in the original cavity, as opposed to non-elastic processes with tamped underground nuclear tests that result in the melting and crushing of rock. Thus, a nuclear explosion conducted in an underground cavity has the potential to decouple energy that otherwise would have created seismic signals.37 During the initial Senate debate in 1999, CTBT opponents claimed that cavity decoupling would allow violator states to clandestinely conduct nuclear test explosions with yields as high 70 kt. Critics of the CTBT cite a 1966 decoupled U.S. nuclear test with a decoupling factor of seventy as the basis for this argument, because the decoupled seismic signal would be below the nominal IMS threshold of 1 kt.38 However, as David Hafemeister has pointed out, the cavity must have a diameter of 200 meters, an area of 0.13 sq. km, and the cavity must be constructed at a depth of 1 km. A cavity with these dimensions has never been constructed, and “it would be essentially impossible to construct one physically or to use such a hypothetical cavity with sufficient secrecy to hide a test.”39 Moreover, regardless of the inherent difficulties of cavity decoupling and radionuclide containment, tests of 20, 50, or 70 kt nuclear devices would generate seismic signals “far above” IMS detection levels, even with a decoupling factor of seventy.40

There are significant issues that a potential violator must address before successfully achieving any decoupling scenario that greatly increase the risk that a violation will be detected. These include avoiding yield excursions (when a nuclear device detonates with a force significantly larger than predicted) that would result in only a partially decoupled test, locating appropriate geological structures, fully containing radionuclides from the explosion, maintaining secrecy within a broad technical workforce, and achieving repetitive decoupled tests that would be necessary to support the development of a “deployable weapon.”41 The 2002 NAS report also stated that, at a given depth “the volume of the cavity has to increase in proportion to the yield to achieve the same decoupling factor, but as yield increases so do the practical difficulties of clandestine cavity construction and radionuclide containment.”42 According to the NAS report, “Accepting the possibility of a cavity decoupled test, we conclude that such an underground nuclear explosion cannot be confidently hidden if its yield is larger than 1 or 2 kilotons.”43 To be sure, decoupling nuclear testing is an approach that will require continued attention from verification specialists, but as the Brookings Institution's Michael O'Hanlon notes, the decoupling approach is arduous and does not ensure a nuclear blast will not be detected; instead, “it simply changes the threshold yield at which it can be heard by American, Russian, and international seismic sensors.”44

Low-Yield Nuclear Testing

Given the capabilities of the IMS and the complementary role played by member states’ NTM of verification, what types of testing could a potential violator conduct with a reasonable chance of non-detection? Further, how would the entry into force of the CTBT affect the U.S. capacity to detect and respond to such tests? Although some NWS initially favored a threshold test ban that would have allowed for certain levels of nuclear explosive testing, negotiators in Geneva eventually agreed that the CTBT would be a zero-yield test ban, meaning that no nuclear testing may result in achieving a nuclear yield. A convergence of several factors produced this outcome, though one significant technical reason for the zero-yield ban was that it would establish a qualitative monitoring criterion (the prohibition of nuclear explosions) as opposed to a quantitative standard (the prohibition of nuclear explosions above a given yield), which could create disagreement over how accurately the yields are determined. While arms control treaties need not be verified with 100 percent certainty in order to be effective, it is important to understand the potential benefits to be gained from nuclear testing that could go undetected by the IMS and NTM.45

According to the NAS report, there are certain accomplishments that both amateur nuclear aspirants and seasoned veterans can achieve with low-yield testing. Hydrodynamic, or subcritical, tests are permissible under the CTBT, as no nuclear yield is generated in the process. These and other types of non-nuclear-explosive tests can be utilized to develop simple gun-type nuclear weapon designs. With hydrodynamic tests, countries with lesser testing experience could obtain data on high explosive lens testing for implosion devices and potentially certify crude unboosted fission devices. Countries with ample testing experience may also achieve limited insights on boosted fission weapons. The United States relies on subcritical testing as one important element of the Stockpile Stewardship Program (discussed below).46

Hydronuclear testing (which produces yields of less than 0.1 ton of TNT) is banned under the CTBT because it results in a very small nuclear yield. The primary utility of hydronuclear testing is to conduct one-point safety tests, which are designed to ensure that the probability of a warhead producing a nuclear yield exceeding 4 pounds TNT equivalent if the high explosive were accidentally detonated is less than one in a million.47 According to the NAS report, these types of tests “are difficult to design and implement for an experienced Nuclear-Weapon State and even more so for states with little or no testing experience.”48 For countries with extensive nuclear testing experience, hydronuclear testing could provide enough data for the validation of unboosted fission weapon designs with yields in the 10-ton range. With slightly larger yields (greater than 0.1 tons but less than 10 tons), experienced countries could validate unboosted nuclear weapon designs with ranges as high as 100 tons. Utilizing very-low-yield testing (greater than 10 tons but less than 1–2 kt), countries with lesser experience could achieve limited improvements in yield/weight ratios, or perform proof tests of small-yield nuclear weapons.49 Testing within this range could allow experienced countries to conduct “studies of boost gas ignition and initial burn, which is a critical step in achieving full primary design yield.”50

Although some critics of the CTBT state that Russian CTBT negotiators subscribed to a different definition of a zero-yield ban that would allow for hydronuclear, or very low-yield testing, this claim has been widely rebuffed by both U.S. and Russian officials. In a prepared statement for the Senate Foreign Relations Committee hearing on the CTBT in October 1999, Ambassador Stephen J. Ledogar, chief U.S. negotiator of the CTBT, stated that at all levels of technicality and security classification, the record is unambiguous; Russia and the other NWS understood clearly the implications of the zero-yield ban.51 Moreover, it is unclear how these tests would adversely affect U.S. national security. Ignoring the absence of evidence that Russia intends to test at critical yields, it is feasible that Russia could conduct low-yield or hydronuclear testing without detection. As explained above, this could allow Russia to validate new low-yield nuclear weapons in the 10–100 kt range. Some have argued that this development would allow Russia to control escalation in the case of a conflict and call into question the U.S. nuclear umbrella.52

Kathleen Bailey and Robert Barker have claimed that, “One to two kilotons can be militarily and politically significant to any proliferator.”53 They argue that commercially available guidance technology allows for the accurate delivery of a 1–2 kt device, which would reap untold destruction against a major population center or strategic location.54 Regardless of the difficulties involved in successfully delivering a 1–2 kt warhead, this scenario would exist with or without the CTBT in place. What is important for this discussion, however, is whether U.S. security would be adversely impacted by clandestine development of low-yield nuclear weapons by sophisticated nuclear weapon states. An excerpt from an interview with General James Cartwright, vice chairman of the Joint Chiefs of Staff and the former head of the U.S. Strategic Command, is quite instructive: “Theoretically, if a ‘grave’ threat to the United States emerged that could be deterred only by a low-yield nuclear weapon, the general might be persuaded to support its development. … However, to date, ‘I haven't seen anything that approaches that,’ Cartwright said.”55

Cartwright also told a reporter in 2005 that, “My priority is not reduced yield. … It's to take the accuracy to the point where conventional can substitute for nuclear.”56 This declaration reflects what many defense analysts consider a revolution in military affairs in which air-delivered, precision-guided munitions have replaced nuclear and ground attacks. Although some U.S. analysts have advocated for new nuclear weapons with new capabilities, such as “bunker busters” and low-yield weapons, funding for these weapons has been eliminated, and there is a lack of political support to restart the programs. The National Defense Authorization Act for fiscal 2008 contained a sense of the Congress resolution that the United States and others should work to reduce both the reliance on nuclear weapons and their overall importance. Moreover, given U.S. conventional superiority and taking into account the vast arsenal of strategic and tactical weapons currently under Moscow's control, it is difficult to envision how Russia's possession of new low-yield nuclear weapons could alter the overall strategic balance.

The NAS study examined the net impact to U.S. national security in three separate scenarios: no CTBT, a strictly enforced CTBT, and a CTBT with evasive testing. For each scenario, nuclear weapons tests by selected states of concern were studied in order to gauge the overall impact of the CTBT on U.S. national security. The results of the analysis are summarized below (see Table 1). The assessment reflects a worst-case scenario that assumes the states in question are intent on clandestinely developing nuclear weapons and are willing to risk detection and the subsequent consequences. It is also important to note that the NAS study was released in 2002, and monitoring capabilities have significantly improved as a result of progress on the IMS and enhanced NTM. Nonetheless, the NAS study concluded, “The worst-case scenario under a no-CTBT regime poses far bigger threats to U.S. security interests—sophisticated nuclear weapons in the hands of many more adversaries—than the worst-case scenario of clandestine testing in a CTBT regime, within the constraints posed by the monitoring system.”57

Table 1 Possible nuclear weapons developments of selected countries under three scenarios.

	With No CTBT	CTBT Strictly Enforced	Evasive Nuclear Testing
India and Pakistan	Perfect boosted fission weapons or thermonuclear weapons in order to greatly magnify the destructive power of their arsenals More efficient use of stockpiled fissionable material	Pursue hydrodynamic or subcritical testing in order to enhance understanding of plutonium and the physics of nuclear weapons Virtually no progress toward developing and stockpiling thermonuclear weapons without testing	Conduct one-point safety tests under decoupled conditions With difficulty, perform proof tests of weapons with yields up to 1–2 kt
China	Improve yield-to-weight ratios; miniaturize nuclear warheads; add multiple warhead missiles	Continue non-nuclear advances in warhead technology (power supplies, arming, fuzing, and firing systems)	Conduct decoupled tests for purposes of stockpile stewardship
Russia	Design and confidently develop new low-yield tactical weapons or weapons with special effects, such as enhanced-radiation weapons Continue testing in order to remanufacture weapons on a longer time line allowing for reduced maintenance costs	Within normal design approaches, Russia could not confidently develop new weaponry while strictly observing the zero-yield test ban	Develop new primary under decoupled conditions (integration with secondary requires testing above threshold levels) If not currently in arsenal, develop light tactical (1–2 kt) or very-low-yield weapons (10–100 ton) with decoupled tests; confidently develop 10-ton weapon with hydronuclear testing
North Korea	Reinitiate development of implosion device Test thermonuclear weapons, which would greatly increase the potential destructive power available from its fissile material stocks	Pursue nuclear weapon–related activities permitted under a CTBT (subcritical and hydrodynamic tests), though NNWS are prohibited from conducting these tests under the NPT	Attempt test of an unboosted implosion weapon with a very low yield, possibly leading toward a design that would produce a yield of a few kilotons
Iran	Complete a progression toward boosted fission weapons or thermonuclear designs	Develop inefficient first-generation fission weapons; can't improve on the material-utilization efficiency or the weight of these weapons without testing	Conceivable progress toward modest improvements in weight and materials utilization efficiency, and possible proof testing of a low-yield fission weapon
Source: National Academy of Sciences, Technical Issues Related to the Comprehenisve Nuclear Test-Ban Treaty (Washington, DC: National Academy Press, 2002), pp. 70–78.

Reliability

A key challenge for the Obama administration is to articulate a coherent, forward-looking vision for the U.S. nuclear stockpile and, more broadly, the entire weapons complex. President Obama is committed to maintaining a strong nuclear deterrent until the path toward nuclear disarmament becomes clear and these weapons cease to exist. This policy dictates that the National Nuclear Security Administration (NNSA) maintain confidence in the safety, security, and reliability of the U.S. stockpile in order to meet annual certification requirements well into the future. Bruce T. Goodwin and Glenn Mara, principal associate directors at LLNL and Los Alamos National Laboratory (LANL), respectively, observe that “the preservation of world peace and the prevention of further proliferation through our extended deterrent umbrella” will be the primary “drivers” that guide the future role of the U.S. arsenal.58

While evidence indicates that the United States currently has the capacity to maintain a credible deterrent, the national strategic goals for the U.S. stockpile have not yet been clearly defined. On May 6, 2009, the Congressional Commission on the Strategic Posture of the United States released its final report. The bipartisan commission examined issues such as U.S. strategic policy and force structure, and although the final report contained numerous recommendations on U.S. nuclear weapons policy, the authors were unable to reach consensus on the CTBT. About half of the commission members supported U.S. ratification, while the remaining members opposed the treaty. The congressionally mandated Nuclear Posture Review, the third official review of U.S. nuclear strategy since the close of the Cold War, will also assess the current state of U.S. strategic forces and their future in national security policy. Together, these documents will provide a more accurate portrait of the responsibilities of the NNSA in its mission of maintaining the reliability of the U.S. stockpile into the future. Whatever the future direction of the U.S. arsenal, the critical issue for this article is whether U.S. ratification of the CTBT would hinder the ability of the United States to maintain confidence in the reliability of its stockpile and provide extended deterrence to its allies while remaining committed to its nuclear deterrent.

Nuclear Testing and Confidence in the U.S. Stockpile

Between 1945 and 1992, the United States conducted more than 1,000 explosive nuclear tests in the atmosphere, underwater, in space, and underground. This is more than the combined total of all other countries’ nuclear tests. The United States has tested in locations ranging from the Marshall Islands in the Pacific Ocean, to the Nevada desert, to salt domes in Mississippi, to the Aleutian Islands off the coast of Alaska. Of the 1,054 nuclear explosive tests officially conducted by the United States, fewer than 8 percent were for the purpose of “safety experiments.” Other tests included a handful (four) related to storage and transportation concerns; VELA-Uniform experiments (seven); joint tests with the United Kingdom (twenty-four); and the Plowshare or peaceful nuclear explosives program (twenty-seven). (VELA-Uniform experiments were designed to improve the U.S. capability to detect and identify underground nuclear explosions, and Project Plowshare was initiated by the Atomic Energy Commission to develop peaceful applications for nuclear explosives, including large-scale engineering and construction and stimulating the production of natural gas.) In other words, the purpose of more than 85 percent of all U.S. nuclear testing was to research and refine new nuclear weapons or to study weapons effects.59 In a limited number of instances during the early years of the Cold War, nuclear testing was used to diagnose and resolve important safety and reliability issues affecting the U.S. nuclear arsenal. Today, the annual stockpile evaluation produced by the NNSA must certify that U.S. warheads do not require nuclear testing for purposes of safety and reliability, which it has.60

However, in 2008 the Department of Defense and Department of Energy (DOE) released a report questioning the long-term U.S. reliance on non-deployed stockpiled weapons to respond to new threats and advocating new warheads and the development of a responsive nuclear infrastructure. The report stated that, “Successive efforts at extending the service life of the current inventory of warheads … can decrease confidence in the nuclear stockpile as the warheads deviate further from baseline designs which were originally validated using nuclear test data.”61 Statistically, the number of performance tests conducted by the United States for each warhead has never been adequate to provide high confidence reliability, and as David Hafemeister notes, the “United States has never known warhead reliability with precision when the warhead entered the stockpile.”62 Furthermore, maintaining confidence in U.S. stockpile safety and reliability has generally been assured through non-explosive nuclear testing and the evaluation of weapon component integrity.63

Stockpile Stewardship

In an effort to sustain the legacy warheads in the U.S. stockpile under a testing moratorium, Congress established the Stockpile Stewardship Program (SSP), as outlined in the fiscal 1994 National Defense Authorization Act. Elements of the program included increased efforts toward gaining advanced computational capabilities in order to enhance simulation and modeling programs, as well as increased support for experimental programs such as subcritical testing, high-energy lasers, and inertial confinement fusion. The program also called for continued support for new facilities and construction projects that could contribute to the experimental base capacity of the United States. Furthermore, the act stipulated that the president must report every year to Congress on any concerns over the safety, security, effectiveness, or reliability of existing U.S. nuclear weapons raised by the DOE, or by scientists and engineers at the national laboratories.

Amid concerns over the long-term capability to maintain the stockpile under the SSP, President Bill Clinton conditioned the intention to negotiate a true zero-yield treaty upon a set of specific safeguards that defined concrete terms in which the United States would support the test ban (see Table 2). The safeguards also specified the circumstances that would necessitate U.S. withdrawal from such a treaty, if the supreme national interest of the United States were jeopardized. Finally, President Clinton established an annual certification requirement, a process that has successfully certified the safety and reliability of the U.S. nuclear stockpile every year since 1996.

Table 2 U.S. CTBT safeguards.

Safeguard A	Ensure a high level of confidence in the safety and reliability of nuclear weapons in the active stockpile through the Stockpile Stewardship Program.
Safeguard B	Maintain exploratory and theoretical nuclear capabilities at nuclear laboratories that will attract and retain human scientific resources.
Safeguard C	Maintain basic capability to return to nuclear testing.
Safeguard D	Continue research and development in order to improve monitoring capabilities.
Safeguard E	Support intelligence-gathering and analytical capabilities that provide information on global nuclear arsenals and nuclear weapons development programs.
Safeguard F	Prepare for the withdrawal from the treaty under the standard “supreme national interests” clause, if the secretaries of defense and energy—advised by the Nuclear Weapons Council, the directors of DOE's nuclear weapons laboratories, and the commander of the U.S. Strategic Command—conclude that a high level of confidence in the safety and reliability of a nuclear weapon type (considered critical to the U.S. nuclear deterrent) could no longer be certified.
Source: White House, Office of the Press Secretary, “Fact Sheet on the Comprehensive Test Ban Treaty Safeguards,” August 11, 1995.

The responsibility of maintaining and enhancing the safety, security, and reliability of the U.S. stockpile lies within the NNSA, established as a semi-autonomous agency under the DOE in 2000. There are currently eight sites across the country that are part of the NNSA complex, each handling different aspects of the SSP as well as other activities, including assisting in nonproliferation efforts and developing naval nuclear reactors. In order to evaluate the condition of warheads, NNSA technicians rely on various methods that include X-ray scattering, deep-penetration digital radiography, accelerated aging studies on plutonium pits, and an Advanced Simulation and Computing program to examine and mitigate stockpile issues.64 The SSP also has established modern laboratory facilities including the Dual-Axis Radiographic Hydrodynamic Test Facility at LANL and the National Ignition Facility at LLNL.65

During the lifetime of a warhead, many issues may arise that threaten its reliability. These problems include insufficient tritium (a radioactive gas that boosts the yield of fission weapons), degradation of high explosives, and failure of trajectory sensors. However, these problems are all related to non-nuclear components of the warhead and are observable without nuclear-explosion testing, albeit with extensive testing, simulation, and other activities permitted under the CTBT.66 According to a report released in April 2007 by the American Association for the Advancement of Science (AAAS), the SSP has enabled the NNSA to accurately surveil and assess the health of the stockpile. The AAAS further stated that the SSP has “made significant advances in the basic science of nuclear weapons performance and the properties of nuclear explosive materials; developed and certified new processes for manufacturing plutonium pits […]; and established, vetted, and applied on an annual basis a systematic process of assessment of the U.S. nuclear stockpile.”67

Warhead Refurbishments and the Life Extension Program

Following the implementation of the U.S. test moratorium in September 1992, new nuclear weapon development was replaced by the Life Extension Program (LEP), with the objective of maintaining the safety and reliability of U.S. warheads through the replacement of certain components with newly manufactured ones that are as close to the original design as possible.68 In the LEP process, the design and military mission of the refurbished warhead remain unchanged, although materials and components may be removed and replaced.69 The W87 warhead for the Minuteman III intercontinental ballistic missile underwent a successful LEP that was introduced into the stockpile in 2004. Although there are “potential minor defects in its arming, fusing and firing system, the safety controls that prepare a nuclear weapon for detonation, which have delayed final assembly,” the first refurbished W76 warhead (for the Trident II D5 submarine-launched ballistic missile) was delivered in September 2008.70 Jeanloz argues that the successful W76 refurbishment is a “testament to the confidence that both the military and nuclear-weapons laboratories have in the process as well as the products of LEPs.”71 The W76 warhead accounts for the largest number of deployed weapons in the U.S. arsenal—approximately 800, or 29 percent.72

The lifetimes of the B61-7 and B61-11 gravity bombs were extended by twenty years as the result of a successfully completed LEP refurbishment.73 Entering service into the U.S. arsenal in January 2009, the refurbished B61-11 is a modified version of the B61-7 that is packaged in a high-strength, earth-penetrator case and has built-in warhead shock resistance. The B61-11 is an extension of the B61 earth-penetrating warhead (EPW) project that began in 1989, and the internal case hardware and components, including the insensitive high explosives physics package and warhead electrical system, are identical to the B61-7.74 However, the B61-11 nose and tail are configured differently, and the B61-7 parachute and gas generator have been eliminated on the B61-11. These modifications support the earth-penetrating mission of the B61-11, which represents the only modified weapon that has entered the U.S. stockpile without nuclear testing.75

Primary Pit Manufacturing Capability and Plutonium Experiments

Thermonuclear warheads constitute the principal element of the enduring U.S. nuclear stockpile, and ensuring the proper functioning of these weapons is paramount to the credibility of the U.S. nuclear deterrent. In a two-stage thermonuclear device, the essential component of the primary stage is a plutonium pit that responds to chemical energy from the detonation of high explosives and releases nuclear energy, creating the “nuclear trigger” for the secondary stage.76 Ensuring synchronization of a conventional explosion around the plutonium shell of a typical pit is critical if the warhead is to perform correctly. Although nuclear weapon components, such as wiring and detonators, age over time, components of this nature “can be easily replaced and their proper functioning can be verified through simulations that make no use of nuclear material.”77 However, the plutonium-bearing pit poses a larger challenge, as explosive testing violates the U.S. moratorium, as well as current obligations under the CTBT.78 The 2002 NAS report states that, although a “primary yield that falls below the minimum level needed to drive the secondary to full output is the most likely potential source of serious nuclear-performance degradation,” increasing the primary yield margins in these weapons would not require nuclear testing.79 Increased primary yield margins can be accomplished through modifications that have already been validated by nuclear tests, such as “changes in initial boost-gas composition, shorter boost-gas exchange intervals, or improved boost-gas storage and delivery systems,” none of which require nuclear testing or place additional burdens on the military in terms of maintenance and deployment.80

The pits used in U.S. warheads since 1952 were manufactured at the Rocky Flats Plant northwest of Denver, Colorado, but production ceased in 1989 due to serious safety and environmental hazards and violations of federal antipollution laws. When efforts to regain production capacity finally coalesced, LANL was tasked by the DOE to take on pit manufacturing at its Technical Area 55 site, the only operational plutonium facility at the time. In order to overcome a number of machining and welding difficulties that subsequently arose at the new site, as well as to comply with updated environmental regulations, the Los Alamos staff opted to employ a casting process to produce the pits, as opposed to the wrought process that had been used at Rocky Flats.81 The 2007 AAAS paper concluded that although some scientists had raised concerns about the casting process, “a sufficient test pedigree for cast pits existed to allow the certification.”82 The first replacement pits for the W88 warhead were certified for entry into the U.S. stockpile in September 2007, constituting the first successfully produced pit certified for the stockpile in eighteen years.83 According to Jeanloz, the manufacturing and certification capability re-established by new laboratory staff through extensive scientific and engineering research, including dynamic studies of fissile material through subcritical experiments, is a “clear indication of the robustness” of the SSP.84

As plutonium ages, it degrades due to radioactive decay, necessitating consideration of the impact of unanticipated degradation on the pits within the stockpile.85 Contributions of the SSP in this area include the “greatly increased understanding of the effects of self-irradiation damage on the structure and properties of plutonium alloys,” as well as the modeling efforts at Los Alamos that “have improved theoretical understanding immensely.”86 Thanks to scientific advances made possible through SSP, such as “experiments, simulations, and analysis of previous nuclear test data,” scientists concluded in 2006 that the performance of U.S. nuclear weapons “would not decline sharply due to plutonium aging effects.”87 Contrary to initial concerns about the impact of plutonium aging on pit reliability, an independent review of a five-year U.S. national laboratory program to evaluate pit lifetimes by the JASONs, a group of scientists that advises the government, concluded that, “Most primary types have credible minimum lifetimes in excess of 100 years as regards aging of plutonium.”88 The review also stated that primaries with “assessed minimum lifetimes of 100 years or less have clear mitigation paths that are proposed and/or being implemented.”89

Limitations Imposed on Stewardship Activities by the CTBT

Whether the administration proceeds with LEPs or the development of another replacement warhead capable of meeting certification requirements without testing, the United States has these options because of the confidence in abilities of the national laboratories and the nuclear weapons complex to maintain the arsenal under a test moratorium using the SSP. According to Jeanloz, the United States has the potential to deploy new warheads without testing by leveraging capabilities established under SSP. He argues that, “With no new military mission, and no need for nuclear-explosion testing, the new design would be an extension of the LEPs now successfully underway, focusing on enhancements in safety, security and maintainability.”90 Goodwin and Mara assert that, “Building on its successes, the SSP is on the path to build a capability that can provide confident certification of reuse weapons or RRWs without nuclear testing or … the need to rely on a particular past nuclear test result.”91 Similarly, the 2002 NAS report stated the United States “has the technical capabilities to maintain confidence in the safety and reliability of its existing nuclear-weapon stockpile under the CTBT, provided adequate resources are made available to the DOE nuclear-weapon complex and are properly focused on this task.”92

There are potential limitations on maintaining confidence in the U.S. stockpile under the CTBT, and disagreement exists over the severity of these limitations as well as the consequent impact on U.S. national security of CTBT ratification. Testifying before the Strategic Posture Commission in early 2009, physicist and longtime defense consultant Richard L. Garwin stated, “It should be recognized that confidence in the reliability of legacy weapons under a responsible stockpile stewardship program is likely to increase with time rather than diminish.”93 Moreover, the 2002 NAS study concluded that skepticism over the ability of stewardship activities to keep pace with the growing needs of an aging stockpile underestimates the current capabilities for stockpile stewardship and the effects of technological progress in advancing these capabilities, and overestimates the role that nuclear testing plays in ensuring stockpile reliability.94

Regardless of the potential limitations imposed by the test ban, ratification of the CTBT would not adversely affect the U.S. capability to respond to any critical decline in the reliability of the U.S. stockpile or a perceived erosion of the U.S. deterrent. The United States currently maintains a twenty-four-month readiness posture for nuclear test preparedness, though the House Appropriations Committee recommended eliminating fiscal 2009 funds for test readiness, citing that the SSP had created a “technically superior alternative to nuclear testing.”95 Furthermore, the standard withdrawal clause stipulated in Article IX of the CTBT requires only six months advance notice be given to all other states parties, the Executive Council, the Depositary, and the UN Security Council, along with a statement explaining the circumstances regarded as jeopardizing that state party's supreme interest. There is an emerging consensus that SSP activities have achieved remarkable success in surveilling stockpiled warheads, therefore any problems that may arise regarding stockpile safety or reliability are likely to be detected, provided appropriate resources are allocated to stewardship activities.

National Security

In response to the Senate's failure to provide its advice and consent to the ratification the CTBT in 1999, President Clinton tasked General John M. Shalikashvili, the former chairman of the joint chiefs of staff, with conducting an examination of the political and technical aspects of the debate, as well as identifying a basis of evidence that would support its reconsideration. The 2002 NAS report was one of several studies commissioned by Shalikashvili, who was serving as special adviser to the president and secretary of state for the CTBT at the time. In a letter addressed to the president following the review, Shalikashvili concluded that the CTBT would serve U.S. national security interests and recommended ratification of the treaty, as he had while serving as chairman of the Joint Chiefs of Staff.96 Contained within Shalikashvili's final report were several recommendations on improving prospects for U.S. ratification, which included addressing “concerns about the CTBT's indefinite duration through a joint Executive-Legislative review of the Treaty's net value for national security” convened ten years after U.S. ratification and at “regular intervals thereafter.”97 It is also important to note that Article VIII of the CTBT stipulates that unless a majority of states parties decides otherwise, states parties shall convene a conference ten years after entry into force to review the operation and effectiveness of the treaty.98 The aim of the conference would be to ensure that the “objectives and purposes in the Preamble and the provisions of the Treaty are being realized,” while taking into account any “new scientific and technological developments relevant” to the CTBT.99

Contributions to U.S. Nonproliferation Objectives

With regard to vital nonproliferation objectives, Daryl Kimball asserts that, “the CTBT will have a strong positive effect on the nonproliferation system.”100 The CTBT would limit NWS nuclear weapon development capabilities and reduce the temptation for other states to engage in nuclear weapon programs in response to testing by a NWS. Kimball also argues that in the absence of a permanent CTBT, China and Russia may resort to testing in order to improve their weaponry, and in the case of China, this may mean the addition of multiple independently targetable re-entry vehicles to its arsenal.101 According to the Shalikashvili report, the CTBT would prevent China from freely testing post-production samples of more advanced nuclear weaponry than exist in its current stockpile, as well as impede any plans to place multiple warheads on mobile missiles. “And while Russia and the United States already have a wide range of nuclear capabilities and knowledge,” the report continues, “the Test Ban Treaty provides insurance against a renewal of the nuclear arms race though ‘third generation’ nuclear designs.”102

Countries capable of producing and reprocessing plutonium or enriching uranium generally are capable of constructing fission bombs, and according to Jeanloz, the CTBT cannot guarantee against the development of fission bombs having an approximate yield of 15 kt—these types of nuclear devices can be developed without nuclear explosive testing. The knowledge is considered widely available, and with the global inventory of separated plutonium at 500 metric tons and highly enriched uranium totaling 1,670 (±300) metric tons, one must also assume that fissile material could be available.103 However, as Michael O'Hanlon notes, “developing advanced weapons—thermonuclear devices, devices capable of being delivered by missile, warheads capable of surviving atmospheric re-entry and still performing correctly—is hard.”104 In fact, states with the most advanced nuclear programs often need several tests and corrective procedures before substantial confidence can be achieved in a given design. Furthermore, as Jeanloz notes, “Plutonium based weapons generally require nuclear explosion testing when new; even well tested designs may require further testing if modifications are made, or the device is in new hands.”105 The Shalikashvili report concluded that the CTBT would constrain the “vertical progression from first-generation fission designs and more advanced fission weapons; to second-generation thermonuclear designs with increasingly sophisticated yield-to-weight ratios; to exotic ‘third-generation’ technologies, such as nuclear explosion-pumped x-ray lasers and enhanced radiation weapons. Experts disagree about how far up this developmental ladder a proliferator could go without testing, but the difficulty would increase dramatically after the first steps.”106 Making it harder for proliferators to test missile-mounted warheads of the type that could threaten the United States and its allies is surely in the national security interest of the United States; it also contributes to international peace and security.

Regarding the need to build international support for U.S. nonproliferation objectives, the Shalikashvili report stated, “Once we ratify the Test Ban Treaty, which the rest of the world views as vital for non-proliferation, we will be better able to enlist cooperation on export controls, economic sanctions, and other coordinated responses to specific problems. International support for military action will also be greater if the United States is clearly making full use of cooperative threat reduction measures, too.”107 According to the report, the CTBT is an essential element of U.S. nonproliferation strategy, which must include the “skillful use of a variety of political, diplomatic, economic, and military responses tailored for particular proliferation problems.”108

Strengthening the International Nonproliferation Regime

The Obama administration has announced its intention to pursue an ambitious arms control agenda, which includes securing CTBT ratification, a follow-on treaty to START, and a verifiable global ban on the production of fissile materials for nuclear weapons. Another policy objective for the administration is strengthening the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), the foundation of the international nonproliferation regime, which has been under stress in recent years over North Korea's 2003 withdrawal and subsequent nuclear tests, the discovery of a nearly complete nuclear reactor—built with North Korean help—in eastern Syria (and destroyed in an Israeli air raid on September 6, 2007), and the ongoing tension between Iran and the IAEA over compliance and transparency issues. The comprehensive test ban has historically been at the top of the international disarmament agenda, and NPT conferences have broken down over lack of progress on the issue. Interestingly, according to the Shalikashvili report, the U.S. failure “to ratify the Test Ban Treaty was one of several factors that put the United States on the defensive at the April 2000 NPT Review Conference and decreased our ability to focus attention on challenges to the non-proliferation regime posed by countries such as Iraq, Iran, and North Korea.”109

Nonetheless, in questioning the value of the CTBT in serving U.S. nonproliferation goals, Jack David, deputy assistant secretary of defense from September 2004 to September 2006, points to disarmament measures already taken by the United States and asks, “Are we to believe that U.S. ratification of the CTBT will persuade, say, North Korea and Iran to respect a testing ban?”110 To be sure, U.S. ratification would have no legal consequence for these countries alone, as the treaty will only take legal effect after its entry into force. It is also difficult to imagine how the entry into force of the CTBT in itself would guarantee North Korean or Iranian compliance with a test ban. Michael O'Hanlon observes that U.S. nuclear restraint does not directly dissuade potential proliferators from testing; nuclear decisions are based more on immediate security concerns and agendas than as a result of a global movement to delegitimize the bomb. However, O'Hanlon states that although regional security concerns will be the primary drivers of national nuclear policy, international norms do have an impact. Sustained international efforts to delegitimize the bomb helped persuade leaders in South Korea, Japan, Taiwan, Argentina, Chile, Brazil, Saudi Arabia, Egypt, and Germany to not seek the acquisition of nuclear weapons.111 Potential proliferator states will be more at ease with the decision to test if the other major powers are also testing. The international community widely “regretted” France and China's final tests in 1996, but following the signature of the CTBT in September of that same year, the subsequent nuclear tests by India and Pakistan (1998) and North Korea (2006) have all resulted in UN Security Council Resolutions condemning the tests, as well as the implementation of varying degrees of economic sanctions.112 Although China and South Korea helped shield North Korea from severe sanctions, including after its withdrawal from the NPT in 2003 and before its 2006 nuclear test, Beijing, Moscow, and Seoul agreed to economic reprisals as a result of the strengthened international norm against testing.113

With regard to the South Asian security environment, one possible consequence of a weakened non-testing norm or a return to testing by NWS is the outbreak of a full-scale arms race in South Asia. Although India and Pakistan have respected their respective unilateral test moratoria since 1998, both countries are substantially advancing their military capabilities, including the continued development of ballistic and cruise missile technology.114 With only limited testing experience, India and Pakistan might use additional nuclear testing to perfect “boosted fission weapons and thermonuclear weapons.”115 Constraining India and Pakistan's development of longer-range, more powerful weapons than already exist in their current stockpiles is worthy of U.S. support. Raymond Jeanloz argues that, “Resumption of testing by either country would most likely provoke equal reaction from the other,” and the consequences for global security of a spiraling arms race in South Asia are severe.116 A test ban with legal standing codifies the international norm of non-testing and is consequently more effective than the existing unilateral moratoria, especially for countries such as China, India, and Pakistan. A declassified National Intelligence Daily document from the U.S. director of central intelligence entitled, “China: Accelerated Nuclear Testing Schedule,” indicates that in the 1990s China linked its decision to move up the schedule of a series of nuclear tests due to increasing international pressure related to the CTBT.117 In sum, legally codifying the international norm of non-testing ensures that any country deciding whether to pursue the path of nuclear weapon development would face greater international pressure than compared to the current test moratorium.

Critics contend that the inherent unverifiability of the CTBT would “encourage rogue state regimes to believe they could pursue nuclear weapons programs with impunity,” and that the “attendant erosion of our deterrent would mean that allied countries—notably Japan, Taiwan and perhaps South Korea—that currently rely on the U.S. deterrent ‘umbrella’ would be more likely to develop their own nuclear weapons.”118 But if there were an “attendant erosion” of the U.S. nuclear deterrent, it would be the result of a political decision, not a technical constraint imposed by a test ban. Contrary to claims that the CTBT would lead to the demise of U.S. extended deterrence and provoke our allies to develop their own nuclear weapons, the Shalikashvili report found that, “Preventing the spread of nuclear weapons demands coordinated actions based on common principles by many nations over many years. Our closest allies see the Test Ban Treaty as something that they have fought for alongside the United States since the days of President Eisenhower.”119 Moreover, “U.S. ratification of the CTBT would receive strong support from nearly all elements of the international community.”120 Some of the very countries that some fear may develop nuclear weapons as a result of U.S. CTBT ratification are those that have been most vocal on disarmament issues and have expressed strong and continual support for the CTBT—namely, Japan and South Korea.

Some have questioned whether allowing for ongoing nuclear explosive testing could fundamentally increase the safety of a given country's stockpile, as U.S. testing experience improved some safety and security issues within the stockpile. In the case of India and Pakistan, would it not be in the best interest of the United States and the international community to increase the safety and security of their nuclear arsenals? The issue arose in October 2007 at the “Reykjavik Revisited” conference hosted by the Hoover Institution. During a presentation on test restraints and verification, former assistant secretary of defense Richard Perle acknowledged the recent entries into the nuclear club (India, Pakistan, and North Korea) and noted that there may well be future NWS. Perle then inquired as to “whether a test ban interferes with the making of existing and potential future stockpiles safer and more secure, and if the answer is yes, how do we figure the tradeoff between the two desirable outcomes.”121

At present, India and Pakistan's nuclear arsenals are quite limited. Though both nations certainly have the incentive to improve their nuclear weaponry, the basis for testing is not actually to enhance the safety and security of these weapons; it is to better understand the physics of the weapons in order to improve military capabilities and potentially introduce new capabilities. With regard to enhancing safety and security, more appropriate measures include supporting “enhanced dialogues between technical experts in the U.S. military and technical experts in the U.S. and some of these other countries,” which to a certain degree has already begun.122 For example, Siegfried S. Hecker, former LANL director, has promoted convening plutonium conferences that are international in character and involve the fusion science communities in the United States and abroad. These conferences do not deal with classified aspects of a given country's nuclear stockpile, and “enhanced technical linkages are hugely beneficial” to improving a weapon's safety and security as well as building confidence between states.123

Nuclear Weapons with New Capabilities and Missions

The international taboo against nuclear testing is arguably stronger than at any point in since the dawn of the nuclear age, and a U.S. resumption of nuclear testing, regardless of the purpose, could lead Russia and China to follow suit if either nation believed its national security interests dictated such action. Richard Garwin, one of the co-creators of the hydrogen bomb, states that both “China and Russia appear quite ready for nuclear explosion testing if the CTBT moratorium should end, and China could add significant military capability from a few tests beyond its current base.”124 Regardless of whether U.S. testing would result in Russian and Chinese reciprocity, and discounting the overall impact on U.S. national security of resumed nuclear testing by the other NWS, the political cost of such a decision would be significant. Therefore, a return to testing by the United States must be necessitated by a critical breakdown in the confidence of stockpile safety or reliability, or because national security dictates a new weapon with new capabilities be developed to counter a new threat. According to Hecker, “If you wanted to design a new modern weapon with new capabilities, in my opinion, in spite of all the computers we have, in spite of all the other great new experiment tools we had, I would … not be willing to certify such a weapon without nuclear testing.”125 From a national security standpoint, this is the cost associated with a test ban. However, the same holds true for every nuclear-capable country. The test ban not only freezes the capabilities of the United States, but also Russia, China, India, and Pakistan, relative to each other.

Some have argued that the United States must develop a new nuclear option for countering hard and deeply buried targets, an idea supported by the 2002 NPR. But the concept of nuclear bunker-busters was rejected by Congress, and many experts have attested to the efficacy of conventional means to address the same threat. Sidney Drell and James L. Goodby point out that buried targets have vulnerabilities that can be exploited, such as “air ducts and tunnel entrances for personnel, equipment, and resources,” which conventional munitions can render inaccessible.126 There is no need for nuclear bunker-busters, and therefore no need to allow them as an argument blocking U.S. ratification of the CTBT.

Conclusion

The arguments against the CTBT fail to undermine the value of the test ban for U.S. interests, as well as for international peace and security. First, when the capabilities of the treaty's monitoring system are combined with national technical means of verification, it is clear that states of concern cannot make advances in nuclear weaponry that would alter the strategic balance vis-à-vis the United States by attempting to evade the treaty. The improvement of U.S. monitoring capabilities through the development of the CTBTO verification regime will only make would-be proliferators less confident in their potential evasion scenarios. By achieving a legal test ban, U.S. leadership would also intensify international pressure on states considering testing options within strategic force modernization programs.

Second, although the CTBT severely constrains the qualitative development of nuclear weapons, the safety, security, and reliability of the U.S. stockpile can be adequately assessed under the SSP. Furthermore, the CTBT would not inhibit the ability of the NNSA to respond to any challenges that may arise in maintaining confidence in the stockpile as its numbers continue to decline and the NNSA transformation leads to a downsized nuclear weapons complex.

Finally, the CTBT serves the national security interests of the United States. Forgoing the option to develop new nuclear weapons with new missions and capabilities does not diminish the U.S. ability to respond to the national security threats of the twenty-first century. The United States can address these challenges more effectively by enhancing intelligence-gathering capabilities, closely coordinating with its allies and the international community on nonproliferation and counterproliferation efforts, and increasing overall U.S. monitoring capabilities. The continued development of the IMS, the growth of an increasingly engaged international scientific community exploring issues in monitoring technology, and improving U.S. national technical means of verification all significantly promote the national security interests of the United States and contribute to international peace and security.

Although the ongoing wars in Iraq and Afghanistan, as well as the economic crisis, will likely dominate the Obama administration's first-term policy agenda, achieving favorable outcomes in the host of challenges facing the United States both domestically and internationally requires an appropriate diplomatic landscape. For example, in order to sustain and increase global support for U.S. nonproliferation initiatives, U.S. credibility on international arms control measures must be restored. Ratification of the CTBT would demonstrate that the United States is committed to its Article VI obligations under the NPT and recognizes that the cessation of explosive nuclear testing is an essential step down this road.

Notes

1. “2008 First Committee Resolutions: Nuclear Weapons: 63/87 (L.55),” Disarmament Diplomacy No. 89 (Winter 2008), <www.acronym.org.uk/dd/dd89/89unnw.htm#87>.

2. Jaap Ramaker served as chairman of the CTBT negotiations during their final phase in 1996. “Interview: Jaap Ramaker, Chairman of the CTBT Negotiations in 1996,” CTBTO, September 20, 2007, <www.ctbto.org/the-treaty/developments-after-1996/interviewjaap-ramakerchairman-of-the-ctbt-negotiations-in-1996/ramaker-1/?textonly=1?>.

3. Senator Jon Kyl, “Defense Authorization” [speech critical of the CTBT], Congressional Record, October 24, 2007, pp. S13357-S13358.

4. Senator Jon Kyl, “Defense Authorization” [speech critical of the CTBT], Congressional Record, October 24, 2007, pp. S13357-S13358.

5. Martha Smith-Norris, “The Eisenhower Administration and the Nuclear Test Ban Talks, 1958–1960: Another Challenge to ‘Revisionism,’” Diplomatic History 27 (September 2003), pp. 524–25.

6. David Hafemeister, “Comprehensive Test Ban Treaty: Effectively Verifiable,” Arms Control Today, October 2008, p. 6.

7. “An Overview of the Verification Regime, Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty,” CTBTO, <www.ctbto.org/verification-regime/background/overview-of-the-verification-regime/page-1/>.

8. CTBTO Preparatory Commission, “World Map,” <www.ctbto.org/map/#ims>.

9. “The CTBT Verification Regime Put to the Test—the Event in the DPRK on 9 October 2006,” CTBTO Highlight, <www.ctbto.org/press-centre/highlights/2007/the-ctbt-verification-regime-put-to-the-test-the-event-in-the-dprk-on-9-october-2006/page-1/?Fsize=a>.

10. Hafemeister, “Comprehensive Test Ban Treaty: Effectively Verifiable,” p. 6.

11. Martin B. Kalinowski, Lawrence H. Erickson, and Gregory J. Gugle, “Preparation of a Global Radioxenon Emission Inventory: Understanding Sources of Radioactive Xenon Routinely Found in the Atmosphere by the International Monitoring System for the Comprehensive Nuclear-Test-Ban Treaty,” ACDIS Research Report, Program in Arms Control, Disarmament, and International Security (ACDIS), University of Illinois at Urbana-Champaign, December 2005.

12. Paul R.J. Saey, Andreas Becker, and Gerhard Wotawa, “North Korea: A Real Test for the CTBT Verification System? Part II: Noble Gas Observations,” CTBTO Spectrum 10 (July 2007), pp. 20–21.

13. Raymond Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,” paper delivered at “Reykjavik Revisited: Steps toward a Nuclear Free World,” Hoover Institution, Stanford, California, October 24–25, 2007, p. 166.

14. Raymond Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,” paper delivered at “Reykjavik Revisited: Steps toward a Nuclear Free World,” Hoover Institution, Stanford, California, October 24–25, 2007, p. 164.

15. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty (Washington DC, National Academy Press, 2002), p. 52.

16. “Integrated On-site Inspection Exercise in Kazakhstan Reaches a Successful Conclusion,” CTBTO Preparatory Commission, Press Release, October 9, 2008.

17. Oliver Meier, “Special Report: Major Exercise Tests CTBT On-Site Inspections,” Arms Control Today, November 2008, p. 32.

18. Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,” p. 163.

19. Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,”, pp. 162–63.

20. Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,”, pp. 162–63.

21. Hafemeister, “Comprehensive Test Ban Treaty: Effectively Verifiable,” p. 6.

22. Rebecca Johnson, Unfinished Business: The Negotiation of the CTBT and the End of Nuclear Testing (Geneva, Switzerland: UN Institute for Disarmament Research, 2009), pp. 148–52. See also NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, p. 42.

23. Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,” p. 163.

24. Gabriele Rennie, “Detecting Underground Changes from Space,” Science & Technology Review, April 2005, pp. 4–11.

25. Hafemeister, “Comprehensive Test Ban Treaty: Effectively Verifiable,” p. 6.

26. Rennie, “Detecting Underground Changes from Space,” pp. 4–11.

27. David Hafemeister, “Is the Nuclear Test Ban Verifiable?” panel discussion hosted by the New America Foundation, January 28, 2009, <www.newamerica.net/events/2009/nuclear_test_ban_verifiable>.

28. Jonathan Medalia, “Comprehensive Nuclear-Test-Ban Treaty: Issues and Arguments,” Congressional Research Service, RL34394, March 12, 2008, pp. 33–35.

29. Andrew Koch, “North Korea Tests Non-Proliferation,” Jane's Defence Weekly, October 18, 2006.

30. David Albright and Paul Brannan, “ISIS Imagery Brief: North Korean Site After Nuclear Test,” Institute for Science and International Security, October 17, 2006, <www.isis-online.org/publications/dprk/dprktestbrief17october2006.pdf>.

31. Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,” pp. 166–67.

32. Kimball, “The CTBT: Achievements, Challenges, and Opportunities.”

33. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, p. 58.

34. Kimball, “The CTBT: Achievements, Challenges, and Opportunities.”

35. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, p. 48.

36. Comprehensive Nuclear-Test-Ban Treaty, opened for signature on September 24, 1996, Protocol to the CTBT, Part III, paras. 1–4, <www.state.gov/t/isn/trty/16513.htm#protocol>.

37. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, p. 46.

38. Lynn R. Sykes, “False and Misleading Claims about Verification during the Senate Debate on the Comprehensive Nuclear Test Ban Treaty,” Journal of the Federation of American Scientists 53 (May/June 2000), <www.fas.org/faspir/v53n3.htm>.

39. Hafemeister, “Comprehensive Test Ban Treaty: Effectively Verifiable,” p. 6.

40. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, p. 48.

41. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, p. 48.

42. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, pp. 46–48.

43. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, p. 48.

44. Michael O'Hanlon, “Resurrecting the Test-Ban Treaty,” Survival 50 (February–March 2008), p. 123.

45. Hans M. Kristensen and Ivan Oelrich, “Lots of Hedging, Little Leading: An Analysis of the Congressional Strategic Posture Commission Report,” Arms Control Today, June 2009, pp. 6–15.

46. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, pp. 67–69.

47. Johnson, Unfinished Business, p. 59.

48. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, p. 67.

49. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, pp. 68–69.

50. Sidney Drell, et al., “Nuclear Testing: Summary and Conclusions,” JASON report, JSR-95-320, MITRE Corporation, August 3, 1995, p. 3, <www.fas.org/programs/ssp/nukes/testing/jsr-95-320testrpt.html>.

51. Stephen J. Ledogar, statement prepared for the Senate Committee on Foreign Relations, “Final Review of the Comprehensive Nuclear Test Ban Treaty,” 106^th Cong., 1^st sess., October 7, 1999, pp. 15–20.

52. John Foster, letter cited in Medalia, “Comprehensive Nuclear-Test-Ban Treaty: Issues and Arguments,” pp. 43–44.

53. Kathleen Bailey and Robert Barker, “Why the United States Should Unsign the Comprehensive Test Ban Treaty and Resume Nuclear Testing,” Comparative Strategy 22 (April 2003), p. 132.

54. Kathleen Bailey and Robert Barker, “Why the United States Should Unsign the Comprehensive Test Ban Treaty and Resume Nuclear Testing,” Comparative Strategy 22 (April 2003), p. 132.

55. Elaine Grossman, “Senior U.S. General Sees High Nuclear Threshold,” Global Security Newswire, October 22, 2007, <gsn.nti.org/gsn/GSN_20071022_58872303.php>.

56. Elaine Grossman, “Senior U.S. General Sees High Nuclear Threshold,” Global Security Newswire, October 22, 2007, <gsn.nti.org/gsn/GSN_20071022_58872303.php>.

57. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, p. 78.

58. Bruce T. Goodwin and Glenn L. Mara, “Stewarding a Reduced Stockpile,” paper presented to the AAAS Technical Issues Workshop, Washington, DC, April 24, 2008, p. 1.

59. “United States Nuclear Tests: July 1945 through September 1992,” DOE/NV-209 (Rev. 15), December 2000, <www.nv.doe.gov/library/publications/historical/DOENV_209_REV15.pdf>.

60. Hydronuclear testing during the 1958–1961 U.S.–Soviet test moratorium led to the discovery of a safety flaw in nine nuclear devices that were rushed into deployment before the moratorium took effect. This was corrected when the moratorium was lifted. Siegfried S. Hecker, co-director of Center for International Security and Cooperation and professor (research), Department of Management Science and Engineering, Stanford University, telephone interview with author, March 9, 2009. See also R.E. Kidder, “Maintaining the U.S. Stockpile of Nuclear Weapons During a Low-Threshold or Comprehensive Test Ban,” LLNL, UCRL-53820, October 1987, <www.fas.org/programs/ssp/nukes/testing/kidderucrl53820.pdf>.

61. “National Security and Nuclear Weapons in the 21st Century,” Department of Energy and Department of Defense, September 2008, p. 2, <www.defenselink.mil/news/nuclearweaponspolicy.pdf>.

62. David W. Hafemeister, “How Much Warhead Reliability is Enough for a Comprehensive Nuclear Test Ban Treaty?” Physics and Society Newsletter 36 (2007), pp. 3–8.

63. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, p. 23.

64. Hafemeister, “How Much Warhead Reliability is Enough for a Comprehensive Nuclear Test Ban Treaty?” p. 6.

65. Daniel Whitten, “DOE Struggles on Big Projects, Result of Gross Mismanagement, GAO Finds,” Inside Energy with Federal Lands, April 2, 2007, p. 9; and “World's Largest Laser Gears up for Ignition Experiments,” News Release, NR-09-03-01, LLNL Public Affairs, March 6, 2009.

66. Hafemeister, “How Much Warhead Reliability is Enough for a Comprehensive Nuclear Test Ban Treaty?” p. 5.

67. AAAS, “The United States Nuclear Weapons Program: The Role of the Reliable Replacement Warhead,” Center for Science, Technology and Security Policy, Nuclear Weapons Complex Assessment Committee, April 2007, p. 14.

68. Goodwin and Mara, “Stewarding a Reduced Stockpile,” p. 2.

69. Sidney D. Drell and Marvin L. Adams, “Technical Issues in Keeping the Nuclear Stockpile Safe, Secure, and Reliable,” in “Nuclear Weapons in 21st Century U.S. National Security,” Report by a Joint Working Group of AAAS, the American Physical Society, and the Center for Strategic and International Studies, December 1, 2008, <cstsp.aaas.org/files/DrellAdamsBrief.pdf>.

70. Ralph Vartabedian, “Nuclear Weapon Retrofit Falters,” Los Angeles Times, May 29, 2009, p. A1. See also “Nuclear Weapons: NNSA and DOD Need to More Effectively Manage the Stockpile Life Extension Program,” Government Accountability Office, GAO-09-385, March 2009, p. 3.

71. Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,” p. 155.

72. Robert S. Norris and Hans M. Kristensen, “Nuclear Notebook: U.S. Nuclear Forces, 2009,” Bulletin of the Atomic Scientists, March/April 2009, pp. 59–69,<thebulletin.metapress.com/content/f64x2k3716wq9613/fulltext.pdf>.

73. NNSA, “NNSA Finishes Refurbishment of B61 Bomb: Program Completed Almost One Year Early,” Press Release, January 9, 2009.

74. GlobalSecurity.org, “Weapons of Mass Destruction (WMD): B61-11 Earth-Penetrating Weapon,” <www.globalsecurity.org/wmd/systems/b61-11.htm>.

75. Robert S. Norris, Hans M. Kristensen, and Joshua Handler, “NRDC Nuclear Notebook: The B61 Family of Bombs,” Bulletin of the Atomic Scientists, January/February 2003, pp. 74–76.

76. Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,” p. 156.

77. O'Hanlon, “Resurrecting the Test-Ban Treaty,” p. 128.

78. Jack Mendelsohn, “Still Bound,” Bulletin of the Atomic Scientists, January/February 2000, p. 42.

79. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, p. 31.

80. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, p. 31.

81. Douglas D. Kautz, David B. Mann, Richard G. Castro, Lawrence E. Lucero, and Steven M. Dinehart, “The Pit Production Story,” Los Alamos Science 28 (2003), pp. 58–62.

82. AAAS, “The United States Nuclear Weapons Program: The Role of the Reliable Replacement Warhead,” p. 22.

83. NNSA, “Rebuilt W88 Warhead Formally Accepted For Use In U.S. Nuclear Weapon Stockpile,” Press Release, September 27, 2007.

84. Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,” p. 156.

85. Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,” p. 156.

86. AAAS, “The United States Nuclear Weapons Program: The Role of the Reliable Replacement Warhead,” p. 22.

87. Goodwin and Mara, “Stewarding a Reduced Stockpile,” p. 2.

88. R.J. Hemley et al., “Pit Lifetime,” MITRE Corporation, JASON Program Office, January 11, 2007, <www.fas.org/irp/agency/dod/jason/pit.pdf>.

89. R.J. Hemley et al., “Pit Lifetime,” MITRE Corporation, JASON Program Office, January 11, 2007, <www.fas.org/irp/agency/dod/jason/pit.pdf>.

90. Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,” p. 157.

91. Goodwin and Mara, “Stewarding a Reduced Stockpile,” p. 6.

92. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, p. 34.

93. Richard L. Garwin, “Draft Testimony to the Congressional Commission on the Strategic Posture of the United States,” January 9, 2009, p. 5, <www.fas.org/rlg/9007TEST1.pdf>.

94. NAS, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, p. 34.

95. U.S. House of Representatives, Committee on Appropriations, Energy and Water Development Appropriations Bill, 2009, 110th Congress, 2nd Session, June 2008, p. 126.

96. General John M. Shalikashvili, special adviser to the president and the secretary of state for the CTBT, “Letter to the President and Report on the Findings and Recommendations Concerning the Comprehensive Nuclear Test Ban Treaty (Shalikashvili Report),” Washington, DC, January 4, 2001.

97. Anthony Aust et al., “A New Look at the Comprehensive Nuclear-Test-Ban Treaty (CTBT),” International Group on Global Security, Netherlands Institute of International Relations Clingendael, September 2008, p. 10.

98. Comprehensive Nuclear-Test-Ban Treaty, Article VIII, paras. 1–2.

99. Comprehensive Nuclear-Test-Ban Treaty, Article VIII, para. 1.

100. Daryl G. Kimball, “Prospects for Ratification of the CTBT by the United States,” September 18, 2007.

101. Daryl G. Kimball, “Prospects for Ratification of the CTBT by the United States,” September 18, 2007.

102. Shalikashvili, “Letter to the President and Report on the Findings and Recommendations Concerning the Comprehensive Nuclear Test Ban Treaty (Shalikashvili Report).”

103. See Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,” p. 167; and “Global Fissile Material Report 2008: Scope and Verification of a Fissile Material (Cutoff) Treaty,” International Panel on Fissile Materials, p. 7.

104. O'Hanlon, “Resurrecting the Test-Ban Treaty,” p. 126.

105. Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,” p. 167.

106. Shalikashvili, “Letter to the President and Report on the Findings and Recommendations Concerning the Comprehensive Nuclear Test Ban Treaty (Shalikashvili Report).”

107. Shalikashvili, “Letter to the President and Report on the Findings and Recommendations Concerning the Comprehensive Nuclear Test Ban Treaty (Shalikashvili Report).”

108. Shalikashvili, “Letter to the President and Report on the Findings and Recommendations Concerning the Comprehensive Nuclear Test Ban Treaty (Shalikashvili Report).”

109. Shalikashvili, “Letter to the President and Report on the Findings and Recommendations Concerning the Comprehensive Nuclear Test Ban Treaty (Shalikashvili Report).”

110. Jack David, “There's No Reason for a Nuclear Test Ban,” Wall Street Journal, February 21, 2009, p. A9.

111. O'Hanlon, “Resurrecting the Test-Ban Treaty,” p. 125.

112. Johnson, Unfinished Business: the Negotiation of the CTBT and the End of Nuclear Testing, pp. 76–79.

113. O'Hanlon, “Resurrecting the Test-Ban Treaty,” pp. 125–26.

114. Sharad Joshi, “Pakistan's Missile Tests Highlight Growing South Asia Nuclear Arms Race, Despite New Confidence Building Measures,” WMD Insights, April 2007, <wmdinsights.com/I14/I14_SA1_PakistansMissile.htm>.

115. Kimball, “The CTBT: Achievements, Challenges, and Opportunities.”

116. Jeanloz, “Comprehensive Nuclear-Test-Ban Treaty and U.S. Security,” p. 168.

117. Director of Central Intelligence, “China: Accelerated Nuclear Testing Schedule,” National Intelligence Daily, February 19, 1993, available in Jeffrey Richelson, “U.S. Intelligence on Russian and Chinese Nuclear Testing Activities, 1990–2000: Prospects of Comprehensive Test Ban Treaty Led China to Accelerate Testing Schedule,” National Security Archive Electronic Briefing Book No. 200, September 22, 2006, <www.gwu.edu/~nsarchiv/NSAEBB/NSAEBB200/index.htm>.

118. Kyl, “Defense Authorization,” October 24, 2007.

119. Shalikashvili, “Letter to the President and Report on the Findings and Recommendations Concerning the Comprehensive Nuclear Test Ban Treaty (Shalikashvili Report).”

120. “Nuclear Weapons in 21st Century U.S. National Security,” Report by a Joint Working Group of AAAS, the American Physical Society, and the Center for Strategic and International Studies, December 2008, p. 7.

121. Richard Perle, comments made during the roundtable presentation, “Test Restraints and Verification: Part 1,” Reykjavik Revisited: Steps Toward a World Free of Nuclear Weapons, Hoover Institution, Stanford, California, October 24–25, 2007.

122. Raymond Jeanloz, comments made during the roundtable presentation, “Test Restraints and Verification: Part 1,” Reykjavik Revisited: Steps Toward a World Free of Nuclear Weapons, Hoover Institution, Stanford, California, October 24–25, 2007.

123. Raymond Jeanloz, comments made during the roundtable presentation, “Test Restraints and Verification: Part 1,” Reykjavik Revisited: Steps Toward a World Free of Nuclear Weapons, Hoover Institution, Stanford, California, October 24–25, 2007.

124. Garwin, “Draft Testimony to the Congressional Commission on the Strategic Posture of the United States,” p. 3.

125. Siegfried S. Hecker, comments made during the roundtable presentation, “Test Restraints and Verification: Part 1,” Reykjavik Revisited: Steps Toward a World Free of Nuclear Weapons, Hoover Institution, Stanford, California, October 24–25, 2007.

126. Sidney D. Drell and James E. Goodby, “What are Nuclear Weapons For? Recommendations for Restructuring U.S. Strategic Nuclear Forces,” Arms Control Association Report, October 2007, pp. 21–22.