Durable institution under fire? The NPT confronts emerging multipolarity

ABSTRACT

The regime built around the 1970 Treaty on the Non-Proliferation of Nuclear Weapons (NPT) has helped curtail the spread of nuclear arms for fifty years. In hindsight, it is remarkable only nine states possess the world’s most powerful weapon. The NPT achieved much success during Cold War bipolarity and U.S. unipolarity in its aftermath. But today, China’s rise and Russia’s resurgence have ushered in a new era of emerging multipolarity. Can the treaty withstand the potential challenges of this dynamic environment? There is a real risk that multipolarity may shake the scaffolding of the nonproliferation regime, presenting a significant test to the NPT’s durability. This article identifies four essential elements of the nonproliferation regime: widespread membership, adaptability, enforcement, and fairness. History suggests bipolarity and unipolarity in the international system largely sustained and promoted these NPT features. When international regimes lack such elements, it sharply curtails their long-term efficacy.

KEYWORDS:

• Nuclear weapons
• nonproliferation
• NPT
• international regimes
• treaties
• multipolarity

International leaders and commentators bemoaning the unraveling of the post-World War II order often overlook the nuclear nonproliferation regime. While this regime receives less attention than trade policy or the global state of democracy, for five decades it has been quite successful preventing states from building nuclear weapons (Budjeryn, 2016; Müller & Schmidt, 2010; Rublee, 2009; Sagan, 1996–1997). The 1970 Treaty on the Non-Proliferation of Nuclear Weapons (NPT) is the foundation of the nuclear nonproliferation regime, the set of institutions and activities aimed at curtailing the spread of nuclear weapons and fissile materials. During treaty negotiations in the 1960s, delegations anticipated many more states would develop nuclear weapons. Over 30 states have explored the nuclear option (Bleek, 2017, p. 8), but only four now have nuclear weapons beyond the five nuclear arms possessors codified by the NPT. Nine nuclear-armed states is a far cry from dozens that would exist if all capable states had pursued nuclear weapons. Moreover, this regime has adapted when weaknesses became apparent, and oftentimes, rules have been enforced and cheaters punished.

Yet, the NPT’s success may be a product of the times. The United States and Soviet Union cooperated during Cold War bipolarity to establish the treaty and promote nuclear nonproliferation (Coe & Vaynman, 2015; Herzog, 2021a; Shaker, 1980). The superpowers did so for strategic rationales, including maintaining their military advantages, retaining influence over allies, and avoiding entrapment in nuclear wars among weaker states (Colgan & Miller, 2019; Kroenig, 2009; Verdier, 2008). The regime expanded for similar reasons under unipolarity and U.S. leadership (Gibbons, forthcoming; Onderco, 2021). Several scholars have pointed to Washington’s prioritization of nonproliferation and its longstanding great power position to explain the NPT’s success (Gavin, 2015; Hunt, forthcoming; Levite, 2002–2003; Miller, 2018).

However, bipolarity and unipolarity no longer characterize the international system. Russia has rebounded from its 1990s domestic turmoil and showcased its military power in the Crimea, Georgia, and Syria. With around 48% of the world’s nuclear weapons (Kristensen & Korda, 2021) and cyber capabilities on display in Estonia in 2007 and during the 2016 and 2020 U.S. presidential elections, Moscow’s influence cannot be ignored. Far from a paper tiger, Russia appears to be a “persistent power” (Kofman & Kendall-Taylor, 2021). Likewise, China’s rapidly growing economy, naval operations in the South China Sea, development of hypersonic missiles, and the vast aspirations of its Belt and Road Initiative highlight Beijing’s role as a great power (Mearsheimer, 2021).

A new environment of “emerging multipolarity” has arrived to challenge the vestiges of the U.S.-led international order. Disputes over human rights norms like the Responsibility to Protect (R2P) and the rise of parallel development banking institutions like the Asian Infrastructure Investment Bank are illustrative (e.g., Pratt, 2021). How the nuclear nonproliferation regime will fare under multipolarity remains an open question. After all, the NPT has so far required significant leadership and cooperation from great powers for its creation and maintenance. The regime’s long-term viability hinges on Russian and Chinese willingness to uphold the status quo.

Successful international regimes are diverse in their institutions, activities, and composition. Some characteristics are common across such regimes; without them, crises of legitimacy and efficacy will likely materialize. This article identifies four salient elements that have been pivotal to the NPT’s success preventing the spread of nuclear weapons: widespread membership, adaptability, enforcement, and fairness. We demonstrate how and why these mechanisms have been integral to the regime. While the dynamics of bipolarity and unipolarity largely helped sustain and promote these features, we explain why the dynamics of multipolarity might do the opposite. Emerging multipolarity thus presents a significant test to the durability of the nuclear nonproliferation regime.

The article proceeds in six sections. First, we review existing research on factors that contribute to international regimes. Then, we offer four sections discussing each of the aforementioned mechanisms. These sections show how specific features underlay the success of the NPT during bipolarity and unipolarity, and they assess treaty prospects in a multipolar international order. Finally, we conclude with implications for nuclear policy.

Designing the nonproliferation regime

Scholars have studied international regimes and identified factors behind their effectiveness that may explain historical successes and challenges ahead of the NPT. They have done so in the context of diverse issues including human rights (Hafner-Burton, 2012), the environment (Breitmeier et al., 2011), and trade (Helfer, 2009). It is difficult to comprehensively list such considerations since numerous issue-specific features may contribute to regimes. On the one hand, regarding the environment, Young (2011, pp. 19854–19857) lists regime dynamism, fairness and legitimacy, private–public partnerships, and institutional interplay. On the other hand, writing about human rights, Moravcsik (1995) points to institutional convergence on common norms and varied enforcement mechanisms.

The extant literature therefore does not provide a universal template for effective international regimes. One useful way to think about designing regimes across issue areas is like baking bread. Not all ingredients are necessary for a successful regime, but most successful regimes contain common ingredients akin to water, yeast, salt, and flour. The absence of such fundamentals sharply curtails long-term efficacy in achieving the regime’s core objectives. The need for basic standards of successful international regimes was widely understood by the NPT negotiators, as outlined in Shaker’s (1980) seminal history of the treaty. We contend that theoretical work offers lessons for the nonproliferation regime, particularly regarding regime characteristics with wide coverage in existing scholarship and cross-domain applications. There is also precedent for nuclear and non-nuclear regime behavior comparisons like Kent’s (2007) analysis of Chinese foreign policy. However, as Koremenos et al. (2001, p. 762) write, “states use international institutions to further their own goals, and they design institutions accordingly.” Regime institutions are what their negotiators make of them; there are compromises over treaty language, provisions, and objectives. States have heterogeneous interests, and key players at the table—especially in multiplayer games—may not desire strictly effective regimes. It is these threats to regime effectiveness that motivate our study of the NPT’s future.

Before laying out elements that may matter most for the nonproliferation regime, it is instructive to define its scope. The regime contains “principles, norms, rules, and decision-making procedures” (Krasner, 1982, p. 185) to constrain the number of states possessing nuclear weapons and fissile materials. Apart from the NPT and International Atomic Energy Agency (IAEA), the regime includes formal architecture and informal components. Some of the most important formal elements include the 1971 Comprehensive Safeguards Agreement (CSA) for all NPT members, the more stringent 1997 Model Additional Protocol (AP) for safeguards, the 1996 Comprehensive Nuclear-Test-Ban Treaty (CTBT), and several regional nuclear-weapon-free zones (NWFZs). Since 2004, United Nations Security Council Resolution 1540 has also required improvements in states’ export control laws. Informal regime elements include the Nuclear Suppliers Group (NSG), an organization regulating nuclear technology sales, and the Proliferation Security Initiative (PSI), an effort promoting cooperative illicit nuclear transfer interdictions.

We identify four elements in the literature that shed light on the NPT’s success limiting the spread of the bomb: widespread membership, adaptability, enforcement, and fairness. These are umbrella categories; for example, enforcement speaks to verification, and widespread membership and fairness speak to regime legitimacy. We carefully selected these categories from the literature because of their relation to the nonproliferation regime and propensity for contestation in a multipolar system. Indeed, as we show, diminishment of each category threatens the effectiveness and durability of global regimes. Readers may, of course, identify other facets of the nonproliferation regime that might be affected by emerging multipolarity. The elements we discuss are not necessarily exhaustive so much as prominent and illustrative of risks associated with changing polarity.

In terms of membership, environmental scholars have found that “maximum winning coalitions rather than minimum winning coalitions” are preferable for preventing free riding off regime public goods (Young, 2011, p. 19855). The nonproliferation regime requires widespread membership to discourage, detect, and prevent illicit nuclear transfers and acquisition. Moreover, regime universalization strengthens underlying norms, encouraging adherence and pressure to conform. Finnemore and Sikkink (1998) therefore explain the power of international institutions and their proponents to trigger “norm bandwagoning” and “norm cascades.” When states join treaties, Lupu (2013) and Fuhrmann and Lupu (2016) show there are often causal effects on compliance, including in the human rights and nuclear domains. And to the extent states comply with regime requirements, widespread membership helps elevate regime objectives in global and regional politics (Haggard & Simmons, 1987). For instance, the rise of the Bretton Woods System was instrumental in popularizing free market economics around the world.

Yet, it is important to remember states opted into the nonproliferation regime at a certain period in history. Changes in the nature of the international system have implications for states’ willingness to join and remain inside of regimes (Keohane, 1982, pp. 331–332). If Russia and China decide certain parts of the U.S.-led nonproliferation regime are no longer in their national interests, it could have serious global ramifications (Horovitz, 2015). In energy politics, for instance, Baccini et al. (2013) demonstrate that inclusion of key actors in regimes affects state membership decisions. A lack of participation or compliance may also produce fears of a state being asymmetrically constrained compared to its rivals (Koplow, 2017). An example is the U.S. refusal to join the 1997 Kyoto Protocol because China did not face similar greenhouse gas emission restrictions. Put differently, it becomes more difficult for Washington to promote the nonproliferation regime if the other great powers do not. Scholars have, after all, shown that “tit-for-tat” strategies are oftentimes preferred in both competitive and cooperative endeavors (Axelrod, 1984).

A second element of effective regimes is capacity to adapt to weaknesses or changing circumstances. Keohane and Victor (2011) predict the ability of the climate change regime to respond to global warming and incorporate both private and public efforts will determine its long-term success. Similarly, Bailey and Revell (2015, p. 842) observe regimes progressing through stages, and eventually “negotiations work toward supplementing the framework convention incrementally through further agreements.” O’Brien and Gowan’s (2012, n.p.) study of effective agreements also found, “In order to persist, and to remain relevant, regimes must change and adapt over time, a process that international agreements help to facilitate.” Over fifty years, the nonproliferation regime has had several instances when members pursued adaptations by developing new institutional arrangements to address nuclear dangers. These events occurred in times of shared U.S. and Soviet leadership during bipolarity and U.S. leadership during unipolarity. They helped inspire confidence in the robustness of the NPT.

But adaptations to international regimes require buy-in from more key players in a multipolar world than in previous eras (Olson, 1965; Oye, 1986). This is especially problematic in the present era, as a former unipole faces challengers with dissimilar interests. U.S. withdrawal from the Joint Comprehensive Plan of Action (JCPOA)—popularly known as the Iran Nuclear Deal—after disagreements over modifications, and past difficulties obtaining Russian and Chinese support for multilateral sanctions on Tehran, highlight this dilemma. In another domain, Hafner-Burton et al. (2011, p. 279) show that human rights regimes may actually be strengthened by allowing flexibility. Potential exemptions on NPT safeguards for nuclear-powered submarines operated by non-nuclear-weapon states are analogous, but it remains unclear if all great powers will be supportive.

A third factor contributing to regime effectiveness is enforcement through punishment and threats. Here, scholars are in cross-domain disagreement. Gilligan (2006) suggests the International Criminal Court may deter violations at the margins despite lacking enforcement. But Herzog (2021c) argues CTBT enforcement gaps prior to entry-into-force have allowed certain states to conduct or consider conducting nuclear test explosions. This argument dovetails with Tallberg’s (2002, p. 611) conclusion about European Union institutions: “Compliance problems are best remedied by increasing the likelihood and costs of detection through monitoring and the threat of sanctions.” Many regimes, however, such as those dealing with human rights (Hafner-Burton, 2012, p. 226), lack adequate enforcement. The environmental literature suggests enforcement is more important when states have strong incentives to cheat (Young, 2011, p. 19855). This finding is relevant to the nonproliferation regime as nuclear weapons are thought to provide existential security and guarantors of national sovereignty (Waltz, 1981). There is also evidence from climate change literature suggesting decision-makers and other elites favor international regimes containing enforcement provisions (Freire et al., 2021).

It should be noted that widespread treaty membership can undermine regimes if not coupled with enforcement. Consider when known human rights abusers join humanitarian regimes; this does not necessarily promote regime objectives (Hathaway, 2002). In the current system of emerging multipolarity, enforcement cracks are already developing in U.S.-led regimes. Russia strongly contested the use of R2P doctrine in Libya and Syria. China provides development assistance to states not adhering to global human rights standards that fail to qualify for International Monetary Fund or World Bank aid (Dreher et al., 2018). Moscow and Beijing essentially have started to provide forum shopping (e.g., Busch, 2007) for dissenters to norms propagated by U.S.-backed regimes, a trend that may affect nonproliferation.

Finally, several scholars identify fairness as integral to regime effectiveness. States generally behave more consistently with norms if they “are widely regarded as the result of a fair and legitimate process and if they concur with widely shared substantive notions of justice” (Neumayer, 2005, p. 928). Young (2011, p. 19857) argues that whether actors perceive “that a regime constitutes a fair deal” matters for compliance. Similarly, Albin (2001, p. 229) finds that just and fair agreements may cause states to comply with them. Two components of Albin’s formulation of justice, “balancing different principles and interests” and “the obligation to honor and comply with freely negotiated agreements,” are especially relevant to the nonproliferation regime.

However, in this special issue, Hanson (2022) and Noda (2022) highlight persistent criticisms the NPT has long faced for perceived double standards and lack of fairness in creating an exclusive club of five nuclear-armed states. As Walker writes (2000, p. 705), the emergence of nuclear weapons “created an unprecedented ordering imperative in international politics,” which resulted in two interrelated orders, “a managed system of deterrence [for those NPT members allowed to have nuclear weapons], and a managed system of abstinence [for everyone else].” These inequalities are in many ways incompatible with shared responsibilities of international society laid out by English School theorists as incentives for regime compliance (e.g., Bull, 1977). Unlike the three previous factors, a multipolar world may promote fairness in obligations and give smaller states more meaningful seats at the bargaining table. Given the current structure of nuclear “haves” and “have-nots” in the NPT regime, evolving claims of fairness may undermine the treaty’s legitimacy. Multipolarity also weakens U.S. influence, allowing for alternatives to Washington’s preferred institutions. The 2021 Treaty on the Prohibition of Nuclear Weapons (TPNW) and its complete ban on nuclear weapons possession provides one example. As discussed by Gibbons (2018), and Egeland (2022) and Pretorius and Sauer (2022) in this issue, the TPNW was driven by the dissatisfaction of the “have-nots” with the “haves” purported lack of progress in fulfilling their NPT Article VI nuclear disarmament commitments.

While institutionalist literature focuses on regime effectiveness, the idea that dominant power leadership is necessary to maintain a strong global regime is consistent with realist theorizing about hegemonic stability theory (HST). HST proponents first argued that a liberal economic system needed support for free trade from a powerful or hegemonic state (Kindleberger, 1974). Generally, HST expects dominant powers to provide systemic order by creating regimes and policing compliance (Krasner, 1976, pp. 322–323). Alongside pervasive beliefs in American decline in the 1970s, HST scholars including Kindleberger (1974), Gilpin (1981), and Krasner (1976) anticipated challenges for global order.

There are prominent detractors of the idea that regime sustainment requires dominant powers (Ikenberry, 2012; Keohane, 1984), but these scholars have not examined the nonproliferation regime in detail. It is true that small states vigorously participated in NPT negotiations (Shaker, 1980). Still, leadership by Washington and Moscow has been pivotal to the success of the treaty through the inducement and coercion of allies, adversaries, and nonaligned states. Bipolarity is itself, of course, not a sufficient predictor of successful nonproliferation. Yet, conditions of bipolarity in the second half of the Cold War were such that cooperation on nonproliferation became possible. When the Americans and Soviets began thinking of bipolarity as stabilizing due to détente and the development of secure second-strike nuclear capabilities, further proliferation could not benefit either side. Incentives to defect in this domain decreased. It then became in their mutual interest to collude and promote the NPT (Coe & Vaynman, 2015; Hunt, forthcoming), and U.S. support remained essential thereafter (Bukovansky et al., 2012; Gibbons, forthcoming; Onderco, 2021). Small states also contributed to nonproliferation talks with Iran and North Korea, but their roles were limited to “backchannel” activities supporting great powers (Herzog, 2021b). Given these observations, what would scholars expect for this U.S.-backed regime in emerging multipolarity?

Structural realism anticipates that the number of poles in the global order shapes conflict propensity, international cooperation, and other systemic dynamics. Multipolarity existed before World I and World War II; bipolarity marked the Cold War period, followed by unipolarity (Monteiro, 2014). Structural realists expected American unipolarity to be fleeting, with balancing against the hegemon (e.g., Mearsheimer, 1990). Scholars have anticipated multipolarity’s emergence for over two decades (e.g., Kupchan, 1998) while also predicting possible U.S.–China bipolarity in the next century. As Posen wrote in 2009 (p. 348), “It seems plausible … that a prolonged period of multipolarity will occur before bipolarity reemerges, if indeed it ever does.” While determining the precise beginning of emerging multipolarity is a fool’s errand, it appears the late 2000s to the late 2010s mark this shift. China and Russia began improving their militaries and asserting their status as world powers through nuclear modernization, conventional military activities (Crimea, Georgia, Syria, South China Sea), cyber operations (Estonia, Office of Personnel Management Hack, 2016 and 2020 U.S. presidential elections), and transnational infrastructure projects (Belt and Road Initiative, Nord Stream 2 Pipeline).

What are the salient features of today’s emerging multipolarity? First, this system is characterized by greater uncertainty about capabilities and intentions. Uncertainty about the capabilities of the most powerful states (Posen, 2009, p. 350) is compounded by new military technologies (Sechser et al., 2019). This can make states less confident about their military might, potentially leading to arms racing. Further, existing powers are unlikely to have clarity about the intentions of emerging powers and will plan for worst-case scenarios. Multipolarity is thus assumed to be less stable than unipolarity (Kupchan, 1998, p. 42).

Second, and pivotally, cooperation becomes more difficult as the number of relevant actors increases (Oye, 1986). Uncertainty about one another’s intentions is only one contributor to these difficulties. Cooperation is even more unlikely when actors have few overlapping interests, a situation compounded by challenger incentives to overturn the former unipole’s preferred regimes as their primary beneficiaries scramble to maintain them. Perhaps it is no wonder the United States, Russia, and China are already engaged in bitter disputes over arms control, human rights, international trade, and norms of sovereignty. In the long run, when multiplayer cooperation cannot be achieved, the odds of a single actor being willing to promote regimes and pay the costs of public goods decreases (Olson, 1965). It is only a matter of time until emerging multipolarity tests the nonproliferation regime.

Widespread membership in the regime

The NPT, cornerstone of the nuclear nonproliferation regime, is nearly universal. By 2021, 190 states were members and just five remained outside the treaty. India, Pakistan, Israel, and North Korea possess nuclear weapons developed outside of the regime; South Sudan is the newest state in the international system. North Korea is the only state to have withdrawn from the treaty, doing so in 2003. The existence of a nearly global treaty that prevented dozens of capable states from building the world’s most powerful weapon (Bleek, 2017; Müller & Schmidt, 2010) did not happen by chance. The United States and Soviet Union—sometimes with allied help—engaged in painstaking diplomacy and coercion to persuade others to join. As we show below, such activities were a feature of Cold War bipolarity and post-Cold War unipolarity. The new era of emerging multipolarity has, however, exposed fissures in the regime.

Consistent with Young’s (2011) discussion of winning coalition size, the NPT requires widespread membership to detect, prevent, and deter illicit nuclear transfers and acquisition. Because of the dual-use nature of nuclear materials and technologies, even small state free riders without nuclear programs (e.g., transshipment points) could have deleterious implications for the regime. Additionally, since the NPT can have causal effects in preventing nuclear pursuit (Fuhrmann & Lupu, 2016), the breadth of its membership often elevates the treaty’s objectives (Haggard & Simmons, 1987). The creation of NWFZs is illustrative as many of these regional arrangements build upon principles enshrined in the NPT. Widespread membership thus contributes to enforcement.

From the start, the NPT involved more than just the great powers. Ireland proposed the creation of the treaty at the UN General Assembly in 1961. Treaty negotiations at the Eighteen Nation Committee on Disarmament (ENDC) in Geneva involved states from the eastern and western blocs alongside nonaligned countries (Herzog, 2021a; Hunt, forthcoming; Shaker, 1980). States like Brazil, Egypt, India, Mexico, and Nigeria were actively involved in discussions and proposed several different treaty provisions. In reality, however, most of the work behind the NPT came from the superpowers. The American and Soviet delegations held private consultations, drafted treaty language in isolation from the ENDC, and regularly rejected nonaligned proposals. One Brazilian diplomat who participated in negotiations summarized:

For the NPT, in my view, there were no negotiations at the ENDC. First, the Americans came with the draft. Then the Soviets came with a draft. And then they came with a joint proposal, and it was clear that they wanted to push it through. They each had the other five states, from NATO and the Warsaw Pact, to make it happen. (as cited in Herzog, 2021a, p. 189)

The central roles assembling the nonproliferation regime played by the United States and the Soviet Union did not stop after negotiations. The bipolar world order gave these states overwhelming influence within their respective blocs to promote the treaty. Moscow was most interested in promoting the NPT among the Warsaw Pact and potential proliferators, such as West Germany and South Africa. Moscow had leverage in the eastern bloc that Washington lacked and at times exerted pressure over its allies to join (e.g., Gheorghe, 2013; Herzog, 2021a; Lanoszka, 2018; Timerbaev, 1999). The Soviets also pushed Egypt to sign (though not ratify) the NPT in 1968 (Rublee, 2009, pp. 110–115) and pressured North Korea to accede in 1985 (Solingen, 2007, p. 118).

Still, NPT historian Jonathan Hunt (forthcoming) argues the Soviet role was “nonetheless secondary” because the effort “relied upon Washington’s global relationships and clout.” Washington had greater international influence and appears to have valued regime universalization more than Moscow, reflecting a recognition of the benefits of global regimes, including the power of norms identified in the literature (Finnemore & Sikkink, 1998; Haggard & Simmons, 1987). As a U.S. General Accounting Office (1980, p. 20) report explains, “countries with little or no nuclear capability or potential are not ignored, as adherence by just one additional state increases by two the difference between the number of parties and nonparties and thereby serves to further isolate the nonparty states.”

While many states recognized the NPT’s value for their security, decision-making about joining the treaty was not so straightforward for many others, including allies of the great powers and nonaligned countries. For several, desire for nuclear technology helped persuade them to join. The Indonesian government expressed disinterest in the NPT for much of the 1970s until it sought civilian nuclear power reactors. In leading the establishment of the NSG in 1975 and strengthening its nuclear export laws, the United States made it difficult for non-NPT members to import nuclear technology and materials. Jakarta’s State Minister for Research and Technology, B. J. Habibie, told the Indonesian parliament in August 1978 the time had come to join. He argued “it is necessary to ratify at this time the NPT … as this will lead to talks on foreign aid, especially for nuclear technology cooperation” (as cited in Gibbons, 2020, p. 291).

Security issues motivated other holdouts. The Japanese government had concerns about accepting asymmetric constraints (e.g., Koplow, 2017), as China had tested a nuclear device in 1964 but did not join the NPT until 1992. Though Japan signed the treaty in 1970, ratification did not occur until 1976. A desire not to foreclose the nuclear option motivated a hawkish faction in Prime Minister Takeo Miki’s Liberal Democratic Party to forestall ratification (Abe, 2020). Ultimately, one of the key tools attenuating domestic opposition was a reaffirmed security assurance from U.S. President Gerald Ford’s administration before Diet ratification debates began. The administration noted, “U.S. nuclear war potential is an important deterrent power toward aggression against Japan,” and Washington “will take charge of the defense of Japan in the case of its being attacked by nuclear or conventional weapons” (as cited in Endicott, 1977, p. 282).

Other states were pushed to join the treaty when the United States became concerned about potential proliferation. In April 1975, South Korea ratified the NPT when Washington declared it would cancel economic and nuclear contracts if Seoul remained outside the treaty. American leaders were worried about South Korea seeking nuclear weapons (Solingen, 2007, p. 91). Washington also pressured Saudi Arabia to join the NPT in 1988 after Riyadh purchased DF-3 missiles from China (Fetter, 1991, p. 7). Because the DF-3 “is an exceedingly inefficient vehicle for the delivery of conventional munitions” (Fetter, 1991, p. 12), and had been designed for nuclear payloads, Washington was unsatisfied by assurances the missiles had been modified for conventional use.

In retrospect, it is unlikely the NPT would have achieved near universalization without persistent American pressure. This influence continued during unipolarity, as Washington leveraged its outsized power in the international system to successfully push for the indefinite extension of the NPT in 1995 (Gibbons, forthcoming; Onderco, 2021). The breadth and reach of the U.S. diplomatic corps, alongside military and economic aid, security guarantees, and nuclear assistance for other states all contributed to widespread NPT membership and buy-in to extending the treaty.

Emerging multipolarity, however, may curtail efforts to expand the nonproliferation regime (Horovitz, 2015) and regimes more generally (Keohane, 1982). As an example, the United States and its allies have promoted the Model AP as the global IAEA safeguards standard for NPT members. The AP is more stringent than previous safeguards in terms of inspector access to the entire fuel cycle and short-notice inspections. When the U.S. government negotiates nuclear supply agreements—as with the United Arab Emirates and Vietnam recently—it pushes states to conclude an AP. But China and Russia have agreed to provide nuclear assistance to states without an AP (Gibbons, 2020, p. 294). Their facilitation of forum shopping is likely to grow as great power competition increases, posing a threat to the nonproliferation regime. Beijing and Moscow have agreed to build reactors for Egypt’s El-Dabaa project (Russian-financed), although Cairo has refused to conclude an AP and engaged in fissile material activities at odds with its safeguards commitments (Findlay, 2015, pp. 75–79). Likewise, Russia financed the Belarusian Astravets nuclear power plant, built by Atomstroyexport, a state-run Russian firm. Like Egypt, Belarus does not have an AP. In emerging multipolarity, Russia and China appear to be prioritizing financial gains and increasing their influence over a widening and deepening—or even maintenance of—the nuclear nonproliferation regime.

Even the United States, long the regime’s main backer, has hurt the cause of widespread membership. It has done so with the CTBT, an important agreement in the regime since prohibiting nuclear explosive testing limits both horizontal and vertical proliferation. The U.S. Senate rejected the test ban in 1999 along party lines. U.S. ratification could potentially encourage other holdouts to join the treaty (e.g., Horovitz & Golan-Vilella, 2010), consistent with Baccini et al.’s (2013) findings in the energy domain. The U.S. government has made significant financial contributions to the CTBT’s International Monitoring System (IMS) (Giovannini, 2021). But some factions do not want to rule out the option to conduct nuclear tests. The influence of emerging multipolarity became clear in May 2020, when the administration of Donald Trump considered the first U.S. test since 1992 due to suspected covert testing by Russia and China (Hudson & Sonne, 2020).

Despite its lack of CTBT ratification, the United States has long been the key player persuading states to join nuclear nonproliferation regime institutions. Whether it will remain as adamant or effective a proponent of nonproliferation in a multipolar world is less certain. Emerging multipolarity increases the number of players in the game, decreases the ability and willingness of great powers to unilaterally promote and enforce regimes, and makes cooperation harder (Olson, 1965; Oye, 1986). In competing for global influence, Russia and China can offer states military technology, economic aid, and nuclear assistance with fewer nonproliferation strings attached. This is in line with what Colgan and Miller (2019, p. 310) refer to as “outbidding,” where dominant states try to outdo others in terms of providing benefits to subordinate states. Weaker powers will be able to play the poles against one another, securing aid and other benefits without making concessions or forswearing future behaviors. Great power competition of this nature is problematic because widespread membership, especially in the NPT and safeguards agreements, is vital to monitoring compliance, ensuring supply-side controls, and maintaining confidence in the regime. And the more widely accepted the agreements, the more powerful their normative sway (Müller & Wunderlich, 2013; Smetana, 2020).

Regime adaptations

Scholars of international regimes agree that adaptability matters both in general (O’Brien & Gowan, 2012) and for specific issues like climate change (Keohane & Victor, 2011) and human rights (Hafner-Burton et al., 2011). A regime’s flexibility determines how states manage both weaknesses that emerge in practice and changes in international circumstances. Scholars have different views on the nonproliferation regime’s adaptability even within this special issue. Smetana and O’Mahoney (2022) argue the NPT is an “antifragile system” that grows stronger with contestation. Knopf (2022) contends the treaty was capable of adapting in the past but has since stagnated. States’ confidence in the NPT regime stems from its ability to combat the spread of nuclear weapons and associated materials and technologies. To contribute to these discussions, we analyze two important regime adaptations: establishment of the NSG during the 1970s under bipolarity and creation of the AP in the 1990s under unipolarity. We compare these attempts to recent regime adaptation efforts and consider the implications of emerging multipolarity.

The NPT’s adaptability was put to the test in May 1974. India, a treaty non-party, used material and technology, imported from the United States and Canada for ostensibly civilian purposes, to conduct Operation Smiling Buddha, a so-called peaceful nuclear explosion. The Indian test made stark the dual-use nature of nuclear technology and demonstrated that even states considered “less developed” could proliferate. In response, U.S. Secretary of State Henry Kissinger initiated the creation of what was first called the London Suppliers Group to coordinate export controls. U.S. leaders consulted with their Soviet counterparts in fall 1974 about hosting a suppliers’ conference and discussing nuclear material security (Gibbons, forthcoming). Unlike the tense early Cold War days, Moscow and Washington were in a period of détente and both possessed sufficient nuclear weapons to ensure a secure second strike. In this environment of relative strategic stability, Moscow had little incentive to thwart U.S. efforts. The suppliers met during the mid-1970s and drafted guidelines for mitigating risks associated with sales of dual-use technology.

The formation of the NSG was the first time U.S. leaders recognized a weakness of the nascent nuclear nonproliferation regime and established an institutional fix. It was, as Bailey and Revell (2015) explain—in principle—in the international regimes literature, a needed step toward developing new institutions to supplement the core of the NPT regime. Unsurprisingly, the plan met some resistance in terms of regime fairness, as many states saw the NSG as undermining access to nuclear technology for peaceful purposes permitted under NPT Article IV. Nonetheless, the NSG has been successful in setting standards on transfers of technologies most suited to nuclear weapons development like those for uranium enrichment and plutonium reprocessing. The group now has 48 member states and over the years has passed more robust rules about nuclear supply. For example, in the early 1990s, the NSG created new guidelines in response to Iraqi proliferation attempts. This effort during the early days of unipolarity “resulted from sustained US leadership” according to Oxenstierna (1999, p. 77). Such flexibility in response to fast-changing world events is in line with scholarship about features that may contribute to successful international regimes (Keohane & Victor, 2011; O’Brien & Gowan, 2012).

Another significant regime adaptation occurred in the 1990s when the international community created a more stringent IAEA safeguards agreement, the Model AP. Like the revision of NSG rules in the 1990s, this effort was instigated after international inspectors discovered the extent of Iraq’s secret nuclear program following the Gulf War. Baghdad’s ability to build this program as an NPT member illustrated weaknesses in existing safeguards. While many members of the international community worked to create the AP, Houck et al. (2010, p. 11) conclude that IAEA negotiating committee success was in part based upon “U.S. leadership and support from the highest levels of the USG.” Russia cooperated on the AP, though Moscow did not demonstrate leadership as it did during negotiations of the 1971 CSA. Still, former IAEA official Laura Rockwood (2017, p. 1) argues, “the greatest achievements in IAEA safeguards have only come about with the support and assistance of the United States and the Soviet Union/Russian Federation.”

A total of 137 states and the European Atomic Energy Community (Euratom) have concluded AP agreements with the IAEA as of October 2021. While significant holdouts include Argentina, Belarus, Brazil, Egypt, Iran, Saudi Arabia, Syria, and Venezuela, most states perceive the AP to be the global safeguards standard. Unlike under CSAs alone, no state with an AP in force has ever been caught cheating on its NPT commitments (Robinson & Gibbons, 2021). The AP is not universal, but its creation was a significant adaptation to the regime championed by great power leadership. Moscow played less of a role than Washington in forming the NSG during bipolarity and in designing the AP during unipolarity, but it still cooperated. Most importantly, it did not impede American efforts to strengthen the regime.

Emerging multipolarity has been more troublesome for those seeking to reform the regime, in large part because of an increased number of key players. This accords with predictions of seminal literature indicating cooperative outcomes become more difficult to achieve as group size increases (e.g., Olson, 1965). After North Korea’s NPT withdrawal in 2003, U.S. leaders promoted strengthening the withdrawal clause of the treaty (Article X). Washington’s concern was that states could accumulate technology for peaceful civilian nuclear energy uses (permitted under Article IV) and then withdraw and use the same technology to build the bomb. American officials presented this idea at the 2010 NPT Review Conference, but it did not go far. Countries like China and Russia, which have much closer relationships with Pyongyang than the United States does, did not champion the initiative. It was apparently in their interests to preserve such ties at the expense of improving the nonproliferation regime’s adaptability.

In recent years, Russia’s increased assertiveness on the international stage has dovetailed with growing resistance to strengthening and streamlining IAEA safeguards (Rockwood, 2014). This task is necessary for an organization with increasing global responsibilities but a flat budget. However, the active support Moscow showed in early safeguards negotiations, and more passive support during the AP negotiations, appears to be waning in emerging multipolarity. In addition, Russia and China have withdrawn their “observer status” in the International Partnership for Nuclear Disarmament Verification (IPNDV), a public–private partnership between the U.S. State Department and the Nuclear Threat Initiative bringing together nuclear-armed and non-nuclear state representatives to explore future verification challenges (Erästö et al., 2019, p. 11). The ability to adapt and the embrace of private sector innovation are criteria listed by Young (2011) in the environmental literature as determinants of a successful international regime. Success may not be possible, however, without participation of the poles of the international system. While it is unlikely that Russia and China desire additional nuclear-armed powers, they have been increasingly uncooperative with American efforts to bolster the regime.

There are several reasons why adapting the nonproliferation regime is difficult even in the best circumstances. Changes require buy-in from a critical mass of states, which necessitates great power promotion and leadership. Recently, China has not taken a strong leadership stand in this domain, and Russia has pushed back against proposed changes with growing frequency. These developments do not bode well for the future of the NPT regime in a multipolar world. Russia and China appear to be privileging relationships with non-nuclear states over promoting nonproliferation. If the great powers cannot cooperate on developing measures to address shortcomings in the regime and rallying support for these ideas, it seems unlikely weaker states will go along with difficult and time-consuming changes.

Nonproliferation enforcement

Enforcement mechanisms are integral to successful international regimes (Hathaway, 2002; Tallberg, 2002) and may contribute to obtaining widespread membership (Freire et al., 2021). After all, many states want to have confidence regimes can achieve their objectives. Young (2011) argues enforcement is only necessary when there are incentives to cheat; the potential of nuclear weapons to ensure state survival provides these incentives. Enforcement has long challenged the nonproliferation regime (Walker, 2000, p. 715), though it has an official enforcement mechanism and ad hoc options. If a state is found in noncompliance with NPT commitments, the IAEA Board of Governors may refer the violator to the United Nations Security Council (UNSC). The UNSC can decide to take action, like imposing sanctions, to attempt to change the state’s behavior. Through the UNSC and unilateral actions, the United States has been the primary enforcer of regime rules. Since the 1970s, Washington has threatened and punished friends and foes alike for proliferation activities. However, these actions seem to be declining in effectiveness as the world transitions to multipolarity.

During the Cold War, Washington threatened South Korea and Taiwan over concerns their governments were engaged in nuclear proliferation despite NPT commitments. South Korea signed the treaty in 1968 and ratified in 1975 under American pressure. As the mid-1970s progressed, U.S. leaders had become concerned about Seoul’s nuclear intentions and worried South Korea’s actions might motivate North Korea and Japan to seek nuclear arsenals (Miller, 2018, p. 111). In 1976, the IAEA found discrepancies in Taiwan’s plutonium declarations, and Taipei sought reprocessing technology for the second time. The U.S. ambassador swiftly threatened to cut off nuclear, military, and economic assistance (Miller, 2014a, p. 56). Taiwan complied and ceased its controversial activities.

Crucially, the Soviet Union did not interfere with U.S. coercion or offer South Korea and Taiwan alternative options for assistance. Although Moscow was less involved in policing the NPT than Washington, the Kremlin sent delegations to Warsaw Pact allies to encourage treaty participation and compliance (e.g., Timerbaev, 1999). There is also evidence that Soviet Premier Leonid Brezhnev and his advisors exerted some amount of pressure on Romania to join the treaty because they believed Bucharest had nuclear ambitions (Gheorghe, 2013; Herzog, 2021a, pp. 113–170). During bipolar stability, neither side saw advantage in disrupting the delicate balance by creating or enabling additional nuclear states, even among allies.

In more recent years, economic sanctions have replaced patron threats as the most-used tool to punish noncompliance as the list of potential proliferators has shifted from U.S. clients to recalcitrant states (Monteiro, 2014). Sanctions are meant to compel changes in target state behavior, but they also aim to send messages to others. Sanctions can be issued by individual states or multilateral organizations like the UNSC and European Union. They are an attractive nonproliferation tool providing coercive leverage without requiring threats or use of military action. In practice, sanctions are often coupled with threats, and the United States has occasionally used force to stymie proliferation (Allison & Bowen, 2021; Kreps & Fuhrmann, 2011). However, Washington has primarily leveraged its central position in the global financial system to impose unilateral sanctions and lead multilateral efforts. The U.S.-orchestrated embargo on Saddam Hussein’s Iraq during the 1990s with UNSC support is illustrative of the latter. Not only can Washington target nearly any state, entity, or individual, but it can impose “secondary sanctions” on actors transacting with the target. Research indicates nonproliferation sanctions have deterred proliferation activities in states that would be most affected by U.S. coercion (Miller, 2014b).

The United States has sanctioned Iran, North Korea, and Syria for proliferation-related activities in recent decades. North Korea and Syria sanctions have generally yielded little, and scholars provide mixed assessments of Iran sanctions. Petrovics (2019, pp. 97, 175) finds both North Korea and Iran intensified nuclear efforts when sanctions were strengthened, though Tabatabai (2017, p. 229) argues “a key reason why Iran returned to the negotiating table [in 2012] was to seek sanctions relief and pave the way for economic recovery.” The 2012 negotiations led to the 2015 JCPOA and Tehran’s agreement to dismantle parts of its nuclear program and submit to more rigorous IAEA inspections in exchange for sanctions relief.

In addition to unilateral sanctions, the United States has often called for UNSC sanctions. Scholars have found multilateral sanctions are more effective than unilateral ones because of the coercive weight of additional state involvement (Bapat & Morgan, 2009). Indeed, multilateral sanctions during bipolarity and unipolarity played a significant role convincing South Africa and Iraq to eventually dismantle their nuclear weapons programs. But under emerging multipolarity, attempts to coerce compliance through multilateral sanctions have so far been less successful. While UNSC sanctions likely contributed to the JCPOA, sanctions against Iran and North Korea have faced hurdles. Russia and China wield UNSC vetoes and have at times resisted taking strong actions. Other times, they have not fully implemented sanctions. The relative gains Moscow and Beijing obtain from trading for Iranian oil and North Korean coal appear to contribute to this trend, but another possibility is that these states benefit from Tehran and Pyongyang occupying an outsized proportion of the U.S. foreign policy agenda. Sanctions defections become more consequential as China’s rise and Russia’s resurgence means the United States and others dedicated to nonproliferation enforcement make up a smaller percentage of the global economy.

After North Korea tested a nuclear device in October 2006, the UNSC sanctioned Pyongyang, banning weapons, missile technology, and luxury goods sales. The body also called for asset freezes and travel restrictions targeting certain North Korean nationals involved in government and nuclear matters. Yet, as Eckert (2009–2010, p. 74) writes, “little was done to enforce the measures,” with each state given implementation responsibility. The UNSC and the United States have continuously imposed stronger sanctions as North Korea produces fissile materials and tests missiles and nuclear devices. These efforts seem to have little effect halting the nuclear program or bringing Pyongyang back into the NPT. In assessing UNSC nonproliferation sanctions, Eckert (2009–2010, p. 74) concludes one important lesson is “the necessity of political will among member states for sanctions to be effective.” Russian and Chinese trading not only helps the North Korean economy, but it suggests to other states that sanctions rules are at least somewhat contestable. In a similar vein, China’s rejection of the PSI and its cooperative nuclear interdiction activities hurts nonproliferation regime enforcement.

U.S. sanctions are powerful due to American economic strength and status in the global financial system. Moreover, UNSC sanctions require political will and leadership from the five permanent members, something the United States has consistently provided more than Russia or China. As U.S. relative power wanes during multipolarity, its sanctioning capabilities will decrease. Target states may look to other powers for aid, providing a forum shopping effect (e.g., Busch, 2007). And when cheaters are not sufficiently punished, it undermines regimes (e.g., Hathaway, 2002) and can shake members’ confidence in their fairness while emboldening the transgressor. The growth of other currencies relative to the U.S. dollar also suggests the efficacy of Washington’s sanctions will continue to decrease. In fact, U.S. reliance on sanctions as a tool of statecraft may even accelerate this process as some states reduce their banking and trading in dollars (McDowell, 2020). Waning U.S. material power and influence, along with reduced great power enforcement cooperation, will likely hurt the nuclear nonproliferation regime in the coming years.

Multipolarity’s contribution to reduced great power cooperation has also manifested in the CTBT context. The United States is the largest financial contributor to the test ban’s IMS although the treaty has not entered into force (Giovannini, 2021). China has withheld data transmission to the international community from all monitoring stations on its territory in past years, though it recently reversed course (Herzog, 2017), and Russia briefly stopped transmissions from some of its radionuclide stations when it tested the Burevestnik nuclear-powered cruise missile (Murphy, 2019). These actions confirm Coe and Vaynman’s (2020) observation that states often prioritize secrecy of their national capabilities over transparent monitoring and verification. This has particular relevance to China and Russia in the current international system, as they are great powers with significantly less military strength than the United States.

Lastly, regime enforcement discussions are incomplete without considering the JCPOA. As noted above, some scholars argue nonproliferation sanctions helped bring Tehran to the bargaining table (Tabatabai, 2017). In a significant achievement of great power cooperation, a deal was finalized in 2015 after a long diplomatic process involving Iran, the United States, China, Russia, Britain, France, and Germany. The Trump administration withdrew the United States from the agreement in May 2018. While it appears that, at least regarding nonproliferation, this withdrawal reflected domestic political machinations, it highlights difficulties in achieving cooperation in multiplayer games (e.g., Olson, 1965; Oye, 1986) and maintaining deals relying on agreement from large numbers of veto players (Herzog, 2021c). The administration of Joe Biden is seeking to revive the JCPOA in some form, but it is unclear how quickly damage to the nonproliferation regime can be repaired. If great powers can withdraw from deals they negotiate, or fail to enforce multilateral sanctions they approve, how long can other states keep their faith in the NPT and its subsidiary institutions?

Regime fairness

The nuclear nonproliferation regime faces significant challenges when it comes to perceptions of fairness (e.g., Hanson, 2022; Noda, 2022; Walker, 2000). While the NPT enumerates members’ rights and responsibilities, it contains bargains triggering ideas about justice and fairness (Albin, 2001), especially given the division between five official nuclear-weapon states and the rest of its members. The NPT is considered to have three main pillars: nuclear nonproliferation, disarmament, and peaceful uses. Nonproliferation is the primary focus of the United States, many of its allies, and other NPT nuclear-armed states; its prioritization over the other pillars has led to charges of unfairness. This matters because fairness perceptions have implications for normative compliance and widespread regime membership (e.g., Neumayer, 2005; Young, 2011). Today, notions of fairness in the regime have evolved, and bargains from times of bipolarity and unipolarity are under scrutiny.

One bargain enshrined in Article IV of the treaty is that all members shall have access to nuclear technology for peaceful civilian purposes. In spite of its clear wording, this article has nonetheless been a point of contention. Due to dual-use concerns, the nuclear-armed states have sought to create additional rules limiting supply, such as those of the NSG and various pieces of national legislation conditionally restricting exports. Support for supply-side restrictions was often robust during times of relatively stable bipolarity and continued under unipolarity, as seen by widespread backing for the Iraq embargo. But in more recent emerging multipolarity, Iran has claimed the right to all peaceful nuclear technology, including gas centrifuges for uranium enrichment, while the United States and its allies seek to restrict “sensitive” technologies (Kaplow & Gibbons, 2015, p. 7). Many states in the developing world view Washington’s maneuvers as infringements on treaty fairness; China and Russia have often provided a sympathetic audience for these grievances.

The most disputed aspect of the regime is Article VI of the NPT calling on members to pursue good faith efforts toward eventual nuclear disarmament (e.g., Pelopidas, 2021, p. 496). Many non-nuclear-weapon states argue the nuclear possessors have not lived up to this bargain after 50 years. As Walker (2000, p. 708) recounts, “The nuclear order’s legitimacy … rested upon mutual obligation and reciprocity. And it rested heavily upon the notion that the possession of nuclear weapons by the five acknowledged powers was a temporary trust and a trust that could be extended to no other nation-state.” Or as Tannenwald (2013, p. 300) aptly puts it, “The core of the justice and fairness problem of the NPT is that what was supposed to be a transformation regime—the transformation to a disarmed world—has become a status quo regime.”

There are two primary objections related to Article VI. The first is that nuclear-weapon states should not be in such a position of power. During the treaty’s negotiation in the 1960s, many states criticized the NPT for creating a two-tiered system limiting status aspirations of developing countries (Herzog, 2021a; Hunt, forthcoming; Shaker, 1980). Likewise, India has raised objections of a “nuclear apartheid” aimed at denying technology, status, and security to states on the basis of race (Biswas, 2001).

The second objection to Article VI deals with perceived slowness of nuclear disarmament, especially among the United States and Russia (Egeland, 2022; Pretorius & Sauer, 2022). Washington and Moscow were able to manage these objections during the bipolar and unipolar eras, achieving the NPT’s indefinite extension in 1995 (Gibbons, forthcoming; Onderco, 2021). In today’s system of emerging multipolarity, however, the United States was unable to prevent the rise of a movement of non-nuclear state officials and activists that pushed for creation of the TPNW banning possession of nuclear weapons by all states (Gibbons, 2018; Herzog et al., 2022). This new treaty entered into force in January 2021 and represents a significant rift among the NPT membership over the pace of disarmament. The five NPT nuclear-armed states have disavowed the ban, but despite their objections, a treaty with a true equality of obligations represents an evolution in fairness within the nonproliferation regime (e.g., Albin, 2001; Egeland, 2017). It is in the spirit of the universalist ideal of “one nation, one vote” (e.g., Haggard & Simmons, 1987, p. 497). This division over disarmament may actually serve to undermine the NPT. A divided membership is less likely to cooperate in promoting the regime, negotiating adaptations, and enforcing the rules.

Though there have been substantial reductions in U.S. and Russian nuclear arsenals since the Cold War, these states possess over 90% of the remaining 14,000 global nuclear weapons (Kristensen & Korda, 2021). The last few decades have shaken many states’ confidence that the NPT nuclear-armed states will pursue disarmament. In 2002, the United States withdrew from the Anti-Ballistic Missile (ABM) Treaty to develop missile defense systems, prompting Russia and China to build new offensive nuclear weapon systems. At the 2005 NPT Review Conference, the George W. Bush administration failed to recommit to the disarmament steps agreed upon by all members at the preceding 2000 conference. And the nuclear-armed states did not make efforts to achieve the majority of the 2010 Review Conference’s 64-step action plan. More recently, the Intermediate-Range Nuclear Forces (INF) Treaty dissolved over accusations of Russian cheating, and strategic nuclear arms control efforts have also stalled.

Complaints about Article VI and the regime’s lack of fairness will be exacerbated by the greater reliance on nuclear weapons likely to accompany emerging multipolarity. The five NPT nuclear-armed states are crafting plans for potential future conflict with one another, and their arsenals have increased in importance. Compared to unipolarity, the current environment features more players, more contingencies, and more advanced nuclear weapons. Russia is developing new nuclear capabilities including the Poseidon underwater drone and Burevestnik nuclear-powered cruise missile. Some of these weapons aim to overcome American ballistic missile defenses, but Russia also sees China as a potential threat (Kühn & Péczeli, 2017, p. 71). Meanwhile, China is enlarging its arsenal—including by developing hypersonic missiles—in part due to fears of U.S. missile defense and counterforce capabilities that may threaten its deterrent’s survivability (e.g., Riqiang, 2020). Under the Barack Obama and Donald Trump administrations, the U.S. Defense Department planned to modernize all three legs of the nuclear triad with new platforms and missiles through the 2080s (e.g., Eckstein, 2019). The Biden administration appears set to continue modernization. The three great powers are not alone. France announced plans for its arsenal to remain viable through the 2090s, and the United Kingdom’s 2021 Integrated Review called for increased nuclear forces.

The narrative around unfairness in the nuclear nonproliferation regime will grow unless the nuclear-armed states cooperate and pursue negotiated reductions. But in this emerging multipolar environment, arms control will become more difficult. Traditionally, the United States and Russia have claimed they are fulfilling their NPT disarmament commitment through bilateral arms control. While many non-nuclear-weapon states are frustrated by the pace of reductions, at least bilateral arms control agreements have led to progressively lower numbers of nuclear weapons. In contrast, renewed great power competition and trilateral tensions mean arms control will remain quite difficult in the coming period (Allison & Herzog, 2020).

Conclusion

This article’s primary implication is that the nuclear nonproliferation regime based around the NPT will likely be weakened by changes in the global distribution of power. The regime has survived and thrived through U.S.–Soviet consensus on nonproliferation in the bipolar era and American leadership after the transition to unipolarity. The world is now best characterized as a state of emerging multipolarity. The United States is experiencing a loss of relative global power and sway as other states rise, but Washington remains the dominant economic and military power. Russia is an assertive power that has greatly improved its military capabilities over the past two decades and possesses nearly half the world’s nuclear arms. China is a global economic power quickly moving toward regional military hegemony. In recent years, Beijing has become increasingly assertive about its interests in its region and beyond. The power dynamics of these three states indicate the arrival of a tense period of emerging multipolarity that is already challenging fundamentals of the nonproliferation regime that have contributed to its efficacy and durability for five decades. The four critical factors for the NPT regime’s success we identified are under fire.

As tensions among the United States, Russia, and China run high, it will be difficult for them to cooperate on expanding membership and enforcing the regime’s constituent agreements. Moscow and Beijing have begun to oppose U.S. designs for the nonproliferation regime with greater frequency in recent years and are poised to benefit from relative gains of partnership with potential proliferators. Moreover, the traditional U.S. tool kit for influencing states’ decisions about regime membership and compliance will become less potent as rivals offer forum shopping and similar benefits with fewer conditions attached. As the great powers compete for global influence, weaker states will be able to pit them against each other, securing benefits without making concessions.

Pursuing regime adaptations will also become more challenging. The historical evidence discussed above demonstrates the necessity of great power cooperation in leading previous regime adaptations, including the formation of the NSG and creation of the AP. Enforcing regime rules, especially within the UNSC, will also require cooperation. Recent trends in sanctions enforcement, however, suggest cause for pessimism. The days of cooperation or minimal interference from Russia and China in U.S. promotion and enforcement of the nonproliferation regime may indeed have passed.

Finally, among the four factors related to regime success we discussed, fairness and justice concerns pose the most pronounced threat to the NPT. Military preparations of the dominant states, rising tensions, and limited cooperation make it less likely these powers will seek nuclear reductions through arms control. This is particularly the case as growing U.S. ballistic missile defense and counterforce capabilities incentivize Russia and China to prioritize their national security over nuclear diplomacy. Frustration over the slowness of disarmament may affect membership and undermine support for adaptations and enforcement. Nonetheless, maintaining the status quo among these other factors may permit some regime continuity. If in emerging multipolarity, however, there is little evidence of pursuing Article VI, the regime will likely lose legitimacy, and the arguments of TPNW proponents will gain traction. Some states may begin to see the ban as superior to the NPT, rather than complementary, due to its equal treatment of states (Pretorius & Sauer, 2021, 2022). Increased support for the ban is especially likely if populations around the world become fearful of arms races and nuclear war as global tensions rise.

What can policy-makers seeking to preserve the nuclear nonproliferation regime do in these trying times? While regime adaptations seem unlikely at present, and enforcement faces significant challenges in Iran and North Korea, steps can be taken to expand membership and improve fairness. Western governments led by the United States should work to persuade AP holdouts to conclude these safeguards agreements, especially while Washington still maintains many tools of influence. A more universal AP among NPT members would increase confidence in the regime during an otherwise challenging period. State participants in the Creating an Environment for Nuclear Disarmament (CEND) working groups should also better publicize their efforts. Similarly, restating the commitment of the Five Permanent Members of the UNSC to avoid nuclear war and achieve eventual nuclear disarmament is important, but it is insufficient. The credibility of Article VI—and the regime as a whole for many ban advocates—depends on the nuclear-armed states providing a viable path toward disarmament. Russia and China rejoining the IPNDV as observers would be a positive step, reaffirming the need to find ways to monitor and verify warhead dismantlement. Further, observer participation by the NPT’s nuclear “haves” at future meetings of the TPNW States Parties could also signal their understanding of the seriousness of the disarmament concerns raised by the “have-nots.”

In general, the United States should attempt to persuade Russia and China that the nonproliferation regime should be a rare area of cooperation, even if other issues remain contentious. If normative arguments are unpersuasive, appeals to self-interest may rule the day. The collapse of the NPT and potential addition of new nuclear states would, after all, decrease the relative power of these players. In sum, the nuclear age is colliding with a new age of emerging multipolarity. Without strong leadership from all three great powers to protect the objectives and health of the NPT, the nuclear nonproliferation regime may simply not survive.

Acknowledgements

The authors are greatly appreciative of comments from Maria Rost Rublee, Carmen Wunderlich, Hylke Dijkstra, Heather Williams, David Minchin Allison, Ariel Petrovics, Jooeun Kim, and two anonymous reviewers.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Rebecca Davis Gibbons

Rebecca Davis Gibbons is an Assistant Professor of Political Science at the University of Southern Maine. Her research focuses on the nuclear nonproliferation regime, arms control, the Treaty on the Prohibition of Nuclear Weapons, and global order. Rebecca’s first book, The Hegemon’s Tool Kit: US Leadership and the Politics of the Nuclear Nonproliferation Regime, is forthcoming with Cornell University Press.

Stephen Herzog

Stephen Herzog is a Senior Researcher at the Center for Security Studies at ETH Zurich and an Associate at the Project on Managing the Atom at the Harvard Kennedy School’s Belfer Center for Science and International Affairs. Stephen is drafting a book manuscript about multilateral nuclear arms control and has other ongoing research on nuclear deterrence and nuclear proliferation.