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ABSTRACT
What are the political and strategic consequences of nuclear deployments overseas? The United States continues to maintain around 200 nuclear warheads in Europe, and some observers have called for the United States to redeploy tactical nuclear weapons to the Korean peninsula. This article reviews the insights from recent research on the effects of foreign-deployed nuclear weapons. It asks two central questions. First, does the evidence support the view that foreign nuclear deployments contribute to deterrence? Second, do these deployments strengthen or undermine the Treaty on the Non-Proliferation of Nuclear Weapons? The evidence suggests that foreign nuclear deployments contribute less to deterrence than previously believed. Further, nuclear deployments probably have mixed effects on proliferation. Unanswered questions for further research include the extent to which nuclear-sharing arrangements reassure allies, and the political and strategic consequences of canceling them.
Acknowledgments
The author is grateful for support from the Nonproliferation Policy Education Center, which originally commissioned this article. For helpful comments on previous drafts, the author thanks Andrew Futter, Jeffrey Lewis, Joshua Pollack, and Henry Sokolski.
Notes
1 For reviews of recent literature on the causes of nuclear proliferation, see Scott D. Sagan, “The Causes of Nuclear Weapons Proliferation,” Annual Review of Political Science 14 (2011), pp. 225–44; and Jacques E.C. Hymans, “Theories of Nuclear Proliferation: The State of the Field,” Nonproliferation Review 13 (November 2006), pp. 455–65.
2 See Hans M. Kristensen, “Non-Strategic Nuclear Weapons,” Special Report No. 3, Federation of American Scientists, 2012, pp. 15–22.
3 Matthew Fuhrmann and Todd S. Sechser, “Signaling Alliance Commitments: Hand-Tying and Sunk Costs in Extended Nuclear Deterrence,” American Journal of Political Science 58 (2014), pp. 919–35.
4 Ibid., p. 926.
5 The discussion in this article focuses on nuclear weapons that were based on foreign territory, but excludes seaborne weapons that may have made foreign port calls.
6 Scott D. Sagan and Kenneth N. Waltz, The Spread of Nuclear Weapons: An Enduring Debate (New York: W.W. Norton, 2013); and Peter R. Lavoy, “The Strategic Consequences of Nuclear Proliferation: A Review Essay,” Security Studies 4 (1995), pp. 695–753; Mark S. Bell and Nicholas L. Miller, “Questioning the Effect of Nuclear Weapons on Conflict,” Journal of Conflict Resolution 59 (2015), pp. 74–92; Scott D. Sagan, The Limits of Safety: Organizations, Accidents, and Nuclear Weapons (Princeton: Princeton University Press, 1993); Bradley A. Thayer, “The Risk of Nuclear Inadvertence: A Review Essay,” Security Studies 3 (1994), pp. 428–93; Graham Allison, Nuclear Terrorism: The Ultimate Preventable Catastrophe (New York: Macmillan, 2004); Kyle Beardsley and Victor Asal, “Winning with the Bomb,” Journal of Conflict Resolution 53 (2009), pp. 278–301; Todd S. Sechser and Matthew Fuhrmann, “Crisis Bargaining and Nuclear Blackmail,” International Organization 67 (2013), pp. 173–95; and Todd S. Sechser and Matthew Fuhrmann, Nuclear Weapons and Coercive Diplomacy (New York: Cambridge University Press, 2016).
7 A recent exchange, for example, considered the usefulness of statistical methods in nuclear security studies. Francis J. Gavin, “What We Talk About When We Talk About Nuclear Weapons: A Review Essay,” H-Diplo/International Security Studies Forum 2 (2014), pp. 11–36; and Matthew Fuhrmann, Matthew Kroenig, and Todd S. Sechser, “The Case for Using Statistics to Study Nuclear Security,” H-Diplo/International Security Studies Forum 2 (2014), pp. 37–54. Both are available at <issforum.org/ISSF/PDF/ISSF-Forum-2.pdf>.
8 See, for example, Sagan and Waltz, The Spread of Nuclear Weapons.
9 For example, see Barry Blechman and Russell Rumbaugh, “Bombs Away: The Case for Phasing Out U.S. Tactical Nukes in Europe,” Foreign Affairs 93 (2014), pp. 163–74; Thomas Karako, “Characteristics of a Future Nuclear Force: Smaller, Lower, Newer, More Diverse, and More Integrated,” in Clark Murdock, Samuel J. Brannen, Thomas Karako, and Angela Weaver, Project Atom: A Competitive Strategies Approach to Defining U.S. Nuclear Strategy and Posture for 2025–2050 (Washington, DC: Center for Strategic and International Studies, 2015), pp. 97–115; and Brent Scowcroft, Stephen J. Hadley, and Franklin Miller, “NATO-Based Nuclear Weapons Are an Advantage in a Dangerous World,” Washington Post (August 17, 2014). In particular, the 2016 coup in Turkey prompted debate about the presence of nuclear weapons there. See, for example, Kori Schake and Jeffrey Lewis, “Should the U.S. Pull Its Nuclear Weapons from Turkey?” New York Times, July 20, 2016, <www.nytimes.com/roomfordebate/2016/07/20/should-the-us-pull-its-nuclear-weapons-from-turkey>.
10 “Working Paper Submitted by the Members of the Group of Non-Aligned States Parties to the Treaty on the Non-Proliferation of Nuclear Weapons,” NPT/CONF.2010/WP.46, April 28, 2010, p. 3.
11 For example, see Shashank Joshi, Iran's Nuclear Trajectory, Whitehall Paper 79, Royal United Services Institute for Defence and Security Studies, 2012, p. 111.
12 “House Panel Calls for Study of Refielding Tactical Nukes in Western Pacific,” Global Security Newswire, May 11, 2012, <www.nti.org/gsn/article/house-committee-backs-redeployment-us-tactical-nukes-western-pacific/>.
13 Here I exclude deployments to territories controlled by the nuclear-armed state in question, such as US deployments to Guam (beginning in 1951), Okinawa (beginning in 1954), Puerto Rico (beginning in 1956), and elsewhere. I also exclude the placement of the first two atomic bombs on the US-controlled island of Tinian during World War II. However, I include the UK deployment of nuclear weapons to its “sovereign base area” at Akrotiri, Cyprus, because the UK government does not classify it as a true dependent territory.
14 Much of what we know about US nuclear deployments abroad comes from a declassified 1978 report from the Department of Defense, partially declassified and released under the Freedom of Information Act. See Office of the Assistant to the Secretary of Defense, “History of the Custody and Deployment of Nuclear Weapons, July 1945 through September 1977,” February 1978, <www.dod.mil/pubs/foi/Reading_Room/NCB/306.pdf>. For a detailed analysis of this document, see Robert S. Norris, William M. Arkin, and William Burr, “Where They Were,” Bulletin of the Atomic Scientists 55 (1999), pp. 26–35 and 66–67; and Robert S. Norris, William M. Arkin, and William Burr, “Where They Were: How Much Did Japan Know?” Bulletin of the Atomic Scientists 56 (2000), pp. 11–13 and 78–79.
15 See the discussion in Hans M. Kristensen, U.S. Nuclear Weapons in Europe: A Review of Post-Cold War Policy, Force Levels, and War Planning (New York: Natural Resources Defense Council, 2005).
16 Kristensen, Non-Strategic Nuclear Weapons. See also Robert S. Norris and Hans M. Kristensen, “U.S. Tactical Nuclear Weapons in Europe, 2011,” Bulletin of the Atomic Scientists 67 (2011), pp. 64–73.
17 Richard Moore, “Where Her Majesty's Weapons Were,” Bulletin of the Atomic Scientists 57 (2001), pp. 58–64.
18 For details, see Matthew Fuhrmann and Todd S. Sechser, “Appendices for ‘Signaling Alliance Commitments: Hand-Tying and Sunk Costs in Extended Nuclear Deterrence,”’ typescript, Texas A&M University and the University of Virginia (2014), <faculty.virginia.edu/tsechser/Fuhrmann-Sechser-AJPS-Appendices.pdf>. The last Soviet nuclear weapons abroad returned home from Mongolia in 1992. J. Enkhsaikhan, “Mongolia's Non-Nuclear Status: An Important Element of Foreign Policy,” Mongolian Journal of International Affairs 16 (2006), pp. 13–25.
19 Treaty on the Non-Proliferation of Nuclear Weapons, March 5, 1970, Article I.
20 See Henry D. Sokolski, Best of Intentions: America's Campaign Against Strategic Weapons Proliferation (Greenwood, CT: Praeger, 2001), especially chapter 4.
21 Daniel Khalessi, “Strategic Ambiguity: Nuclear Sharing and the Secret Strategy for Drafting Articles I and II of the Nonproliferation Treaty,” Nonproliferation Review 22 (November 2015), pp. 421–39.
22 Letter from the Under Secretary of State (Katzenbach) to Secretary of Defense Clifford, Document No. 232, Foreign Relations of the United States, 1964–1968, Volume XI: Arms Control and Disarmament (Washington, DC: US Department of State), p. 573.
23 Dean Rusk, “Questions on the Draft Non-Proliferation Treaty Asked by US Allies together with Answers Given by the United States,” NPT Hearings 90–92 (Washington, DC: United States Senate, 1968), pp. 262–63. Likewise, Defense Secretary Robert McNamara argued before Congress in 1966 that “there is no conflict” between nuclear sharing and nonproliferation. Robert S. McNamara, “Statement of Secretary of Defense Robert S. McNamara before the Joint Committee on Atomic Energy on the Nonproliferation of Nuclear Weapons,” March 7, 1966.
24 NATO, “NATO's Position Regarding Nuclear Non-Proliferation, Arms Control, and Disarmament and Related Issues,” October 22, 2009, <www.nato.int/nato_static/assets/pdf/pdf_topics/20091022_NATO_Position_on_nuclear_nonproliferation-eng.pdf>.
25 This was not always the case: in the 1950s, West German pilots had virtual control of their nuclear bombs when their aircraft were placed on alert. See Norris, Arkin, and Burr, “Where They Were,” p. 30.
26 In dual-key arrangements, an ally's nuclear warheads are assigned to delivery vehicles owned and operated by the host nation. The arrangement effectively gives the host nation the ability to veto the use of nuclear weapons, without being able to unilaterally order their use. Peter Stein and Peter D. Feaver, Assuring Control of Nuclear Weapons: The Evolution of Permissive Action Links (Lanham, MD: University Press of America, 1989). On the US interpretation of NPT rules regarding dual-key arrangements, see Martin Butcher, Nicola Butler, Oliver Meier, Otfried Nassauer, Dan Plesch, Georg Schöfbänker, and Stephen Young, “NATO Nuclear Sharing and the NPT: Questions to Be Answered,” Project on European Non-Proliferation, Research Note 97–3, June 1997, <www.bits.de/public/researchnote/rn97-3.htm>.
27 Charles E. Johnson, U.S. Policies on Nuclear Weapons, Lyndon B. Johnson Library (December 12, 1964), partially declassified and released under the Freedom of Information Act. Quoted in Martin Butcher, Otfried Nassauer, Tanya Padberg, and Dan Plesch, “Questions of Command and Control: NATO, Nuclear Sharing, and the NPT,” Project on European Non-Proliferation Research Report 2000.1, March 2000, <www.bits.de/public/pdf/00-1command.pdf>, p. 20.
28 Rusk, “Questions on the Draft Non-Proliferation Treaty.” The US assertion of a wartime exception to the NPT, however, is dubious. The text of the treaty contains no explicit exception for times of war, and the United States has entered several major conflicts since 1970 without claiming exemption from the treaty. Although Article X allows state parties to withdraw from the NPT due to “extraordinary events,” they are required to give three months’ notice of intent to exit, which would seem to rule out abruptly withdrawing from the treaty in the moments before transferring control of nuclear weapons to allied pilots.
29 Butcher, Nassauer, Padberg, and Plesch, “Questions of Command and Control,” p. 15.
30 See the country reports in Paolo Foradori, ed., Tactical Nuclear Weapons and Euro-Atlantic Security: The Future of NATO (New York: Routledge, 2013).
31 Madeleine Albright, Statement before the Senate Committee on Appropriations, “North Atlantic Treaty Organization Enlargement,” 105th Cong., 1st Sess., October 21, 1997, p. 73.
32 On security motivations for proliferation, see, for instance, Zachary S. Davis and Benjamin Frankel, eds., The Proliferation Puzzle: Why Nuclear Weapons Spread and What Results (New York: Routledge, 1993); and Sagan, “Why States Build Nuclear Weapons.”
33 For instance, see Butcher, Nassauer, Padberg, and Plesch, “Questions of Command and Control.”
34 Steven E. Miller, Nuclear Collisions: Discord, Reform and the Nuclear Nonproliferation Regime (Cambridge, MA: American Academy of Arts and Sciences, 2012), p. 20.
35 See, for instance, William C. Potter and Nikolai Sokov, “Nuclear Weapons That People Forget,” New York Times, May 31, 2000, <www.nytimes.com/2000/05/31/opinion/nuclear-weapons-that-people-forget.html>; Robertus C.N. Remkes, “The Security of NATO Nuclear Weapons: Issues and Implications,” in Steve Andreasen and Isabelle Williams, eds., Reducing Nuclear Risks in Europe: A Framework for Action (Washington, DC: Nuclear Threat Initiative, 2011), pp. 66–75; Eric Schlosser, “Nuclear Weapons: An Accident Waiting to Happen,” the Guardian, September 14, 2013, <www.theguardian.com/world/2013/sep/14/nuclear-weapons-accident-waiting-to-happen>; and Blechman and Rumbaugh, “Bombs Away,” among many others. For fascinating—and terrifying—descriptions of accidents involving foreign-deployed nuclear weapons during the Cold War, see Scott D. Sagan, The Limits of Safety: Organizations, Accidents, and Nuclear Weapons (Princeton: Princeton University Press, 1993); Norris, Arkin, and Burr, “Where They Were;” and Eric Schlosser, Command and Control: Nuclear Weapons, the Damascus Accident, and the Illusion of Safety (New York: Penguin, 2013).
36 For a good summary, see Jaswant Singh, “Against Nuclear Apartheid,” Foreign Affairs 77 (1998), pp. 41–52.
37 Seongwhun Cheon, “Regional Non-Nuclear Options from South Korea's Perspective,” in Young Whan Kihl and Peter Hayes, eds., Peace and Security in Northeast Asia: The Nuclear Issue and the Korean Peninsula (London: M.E. Sharpe, 1997), pp. 393–94.
38 Philipp Bleek and Eric Lorber, “Can Security Assurances Prevent Allied Nuclear Proliferation?” Journal of Conflict Resolution 58 (2014), pp. 429–54; and Jeffrey W. Knopf, ed., Security Assurances and Nuclear Nonproliferation (Palo Alto: Stanford University Press, 2012).
39 For a discussion of these demand-side drivers of proliferation, see Scott D. Sagan, “Why Do States Build Nuclear Weapons? Three Models in Search of a Bomb,” International Security 21 (1996/1997), pp. 54–86.
40 As one scholar put it, “Why would a country like West Germany place greater faith in the puny nuclear forces of its middle-power allies across the Rhine River than in the massive arsenal of its superpower ally? The ultimate implication of a Western Europe minus the United States, therefore, is a nuclear-armed Federal Republic with other Western European countries to follow.” Josef Joffe, “Europe's American Pacifier,” Foreign Policy 54 (Spring 1984), pp. 64–82. See also Bruno Tertrais, “Nuclear Proliferation in Europe: Could it Still Happen?” Nonproliferation Review 13 (November 2006), pp. 569–79.
41 Michael J. Siler, “U.S. Nuclear Nonproliferation Policy in the Northeast Asian Region during the Cold War: The South Korean Case,” East Asia 16 (1998), pp. 41–86; Rebecca K.C. Hersman and Robert Peters, “Nuclear U-Turns: Learning from South Korean and Taiwanese Rollback,” Nonproliferation Review 13 (November 2006), pp. 539–53; Joe Wood, “Persuading a President: Jimmy Carter and American Troops in Korea,” Studies in Intelligence 40 (1996), <http://nsarchive.gwu.edu/NSAEBB/NSAEBB431/docs/intell_ebb_002.PDF>.
42 Dan Reiter, “Security Commitments and Nuclear Proliferation,” Foreign Policy Analysis 10 (2014), pp. 61–80.
43 Reiter, “Security Commitments and Nuclear Proliferation,” p. 77.
44 Matthew Fuhrmann and Todd S. Sechser, “Nuclear Strategy, Nonproliferation, and the Causes of Foreign Nuclear Deployments,” Journal of Conflict Resolution 58 (2014), pp. 455–80.
45 Although Morocco was a French protectorate when the United States first deployed nuclear weapons there in 1954, the French government was not informed of the deployment. See Norris, Arkin, and Burr, “Where They Were,” p. 29.
46 It is also possible that nuclear states may be less likely to deploy nuclear weapons to states seen as potential proliferation risks. However, Fuhrmann and I do not find evidence for this hypothesis. See Fuhrmann and Sechser, “Nuclear Strategy, Nonproliferation, and the Causes of Foreign Nuclear Deployments.”
47 For instance, NATO's recently departed secretary general argued in 2010 that “the presence of US nuclear weapons in Europe is an essential part of a credible deterrent.” NATO Transcript, “Press Conference by NATO Secretary General Anders Fogh Rasmussen at the Informal Meeting of NATO Foreign Ministers—Tallinn, Estonia,” April 22, 2010, <www.nato.int/cps/en/natolive/opinions_62810.htm>.
48 See, for example, Stephen D. Biddle and Peter D. Feaver, Battlefield Nuclear Weapons: Issues and Options (Lanham, MD: University Press of America, 1989).
49 Glenn H. Snyder, Deterrence by Denial and Punishment (Princeton, NJ: Center of International Studies, 1959).
50 Albert C. Wohlstetter, “Nuclear Sharing: NATO and the N + 1 Country,” Foreign Affairs 39 (April 1961), p. 383; and Paul J. Bracken, The Command and Control of Nuclear Forces (New Haven: Yale University Press, 1983).
51 Thomas C. Schelling, “Nuclear Strategy in Europe,” World Politics 14 (April 1962), pp. 421–32.
52 James D. Morrow, “Alliances, Credibility, and Peacetime Costs,” Journal of Conflict Resolution 38 (June 1994), pp. 270–97.
53 For example, see Stephen C. Schwartz, Atomic Audit: The Costs and Consequences of U.S. Nuclear Weapons since 1940 (Washington, DC: Brookings Institution Press, 1998); Tom Sauer and Bob van der Zwaan, “U.S. Tactical Nuclear Weapons in Europe after NATO's Lisbon Summit: Why Their Withdrawal Is Desirable and Feasible,” International Relations 26 (March 2012), pp. 78–100; and Blechman and Rumbaugh, “Bombs Away.”
54 Barry O’Neill, “The Intermediate Nuclear Force Missiles: An Analysis of Coupling and Reassurance,” International Interactions 15 (1990), pp. 345–63.
55 Fuhrmann and Sechser, “Signaling Alliance Commitments.”
56 The study evaluated the likelihood of violent militarized challenges against all states in the international system between 1950 and 2000. It built a statistical model of militarized conflict that controlled for factors such as non-nuclear allies, indigenous nuclear capabilities, geography, political alignment, and regime type.
57 Sam Peltzman, “The Effects of Automobile Safety Regulation,” Journal of Political Economy 83 (August 1975), pp. 677–725.
58 Glenn H. Snyder, “The Security Dilemma in Alliance Politics,” World Politics 36 (July 1984), pp. 461–195. The argument for a connection between nuclear weapons and Peltzman's research is made at greatest length in Jeffrey Lewis, “Frenemies: The North's Nuclear Test Was Bad Enough, The South Shouldn’t Make It Worse,” 38North.org, February 23, 2013, <http://38north.org/2013/02/jlewis022613/>.
59 Some of Castro's most provocative actions are recounted in Michael Dobbs, One Minute to Midnight: Kennedy, Khrushchev, and Castro on the Brink of Nuclear War (New York: Alfred A. Knopf, 2008).
60 Brett V. Benson, “Unpacking Alliances: Deterrent and Compellent Alliances and Their Relationship with Conflict, 1816–2000,” Journal of Politics 74 (July 2011), pp. 427–39.
61 Matthew Fuhrmann and Todd S. Sechser, “The Moral Hazard Myth: Nuclear Umbrellas and Reckless Allies,” presented at the Annual Meeting of the International Studies Association, Toronto, March 26–29, 2014.
62 Brett V. Benson, Constructing International Security: Alliances, Deterrence, and Moral Hazard (New York: Cambridge University Press, 2012); Songying Fang, Jesse C. Johnson, and Brett Ashley Leeds, “To Concede or to Resist? The Restraining Effect of Military Alliances,” International Organization 68 (August 2014), pp. 775–809.
63 Fuhrmann and Sechser, “The Moral Hazard Myth.” However, Rupal Mehta and Neil Narang find that states with nuclear allies are somewhat more likely to initiate militarized crises, though those crises are less likely to escalate to violence. See Rupal N. Mehta and Neil Narang, “The Unforeseen Consequences of Extended Deterrence: Moral Hazard in a Nuclear Client State,” typescript, University of Nebraska and University of California, Santa Barbara, 2015.
64 See, for example, Blechman and Rumbaugh, “Bombs Away.”
65 See Giorgio Franceschini and Harald Müller, “Germany,” in Foradori, ed., Tactical Nuclear Weapons and Euro-Atlantic Security, pp. 44–60.
66 For example, Julian Borger, “South Korea Considers Return of U.S. Tactical Nuclear Weapons,” the Guardian, November 22, 2010, <www.theguardian.com/world/2010/nov/22/south-korea-us-tactical-weapons-nuclear>; Robert Einhorn and Duyeon Kim, “Will South Korea Go Nuclear?” Bulletin of the Atomic Scientists Online, August 15, 2016, <thebulletin.org/will-south-korea-go-nuclear9778>.
67 For example, Petr Suchy and Bradley A. Thayer, “Weapons as Political Symbolism: The Role of U.S. Tactical Nuclear Weapons in Europe,” European Security 23 (2014), pp. 509–28.
68 See United States Department of Defense, Nuclear Posture Review Report (April 2010), pp. 27, 28, and 32.
69 Secretary of Defense Task Force on DoD Nuclear Weapons Management, Report of the Secretary of Defense Task Force on DoD Nuclear Weapons Management, Phase II: Review of the DoD Nuclear Mission (December 2008), p. 59.
70 Mustafa Kibaroglu, “Isn’t it Time to Say Farewell to Nukes in Turkey?” European Security 14 (2005), pp. 443–57.
71 Quoted in Clark A. Murdock and Jessica Yeats, “Exploring the Nuclear Posture Implications of Extended Deterrence and Assurance,” Center for Strategic and International Studies, November 2009, <https://csis-prod.s3.amazonaws.com/s3fs-public/legacy_files/files/publication/100222_Murdock_NuclearPosture_Print.pdf>. In this view, foreign nuclear deployments may be an example of a “path-dependent” phenomenon: a course of action that, once initiated, becomes increasingly costly to reverse over time. Paul Pierson, “Increasing Returns, Path Dependence, and the Study of Politics,” American Political Science Review 94 (June 2000), pp. 251–67.
72 One useful attempt to think about this problem is Malcolm Chalmers and Andrew Somerville, eds., If the Bombs Go: European Perspectives on NATO's Nuclear Debate, Whitehall Report 1–11 (Royal United Services Institute for Defence and Security Studies, 2007).