Nuclear proliferation is not a binary outcome with uniform consequences, but instead spans a continuum of latent capacity to produce nuclear weapons. At various thresholds of technical development, some countries leverage nuclear latency to practice coercive diplomacy. How and when does nuclear technology provide a challenger with the most effective means to extract concessions in world politics? This article claims that compellence with nuclear latency puts a challenger on the horns of a credibility dilemma between demonstrating resolve and signaling restraint, and identifies a sweet spot for reaching an optimal bargain where the proliferation threat is credible while the assurance costs of revealing intent are low. Historical studies of South Korea, Japan, and North Korea validate this Goldilocks principle and find that it consistently reflects the ability to produce fissile material. Contrary to conventional wisdom about proliferation, nuclear technology generates political effects long before a country acquires nuclear weapons.

Tristan Volpe
Tristan Volpe is a nonresident fellow at the Carnegie Endowment for International Peace and assistant professor of defense analysis at the Naval Postgraduate School.
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When does nuclear technology provide a country with bargaining leverage in world politics? In the past, nations have attempted to compel concessions from the United States by wielding the threat of nuclear proliferation. Some governments played the nuclear card by choice as part of a compellence strategy. During the Cold War, officials in Rome and Tokyo threatened to retain unrestricted civil nuclear programs to pressure Washington into complying with various requests, from enhanced military assistance under the NATO alliance for Italy, to the territorial reversion of Okinawa in the case of Japan.1 The South Koreans tried to acquire a plutonium capability to prevent the withdrawal of US forces in the early 1970s. In June 1979, officials at the US Department of State believed that Pakistan’s quest for nuclear technology was driven, in part, by a desire to acquire “a ‘bargaining chip,’ and that the [government of Pakistan] might be willing to hold its nuclear capability at a stage short of actual weapons development” for the right price.2 In the early 1990s, North Korea threatened to produce plutonium for nuclear weapons unless US officials provided energy assistance. Much more recently, Saudi Arabia promised to match Iran’s uranium enrichment capability in 2015 to gain leverage over the White House in negotiations for a formal defense treaty and conventional weapons.

Other nations engaged in coercive diplomacy as a tactical response to alleviate pressure or buy time. The North Koreans returned to concession-seeking diplomacy during the Six-Party Talks after a US delegation confronted them with evidence of a covert enrichment program. In 2003, Libya traded its uranium gas centrifuge program away for sanctions relief, while the revelation of covert nuclear facilities in Iran forced Tehran to open a diplomatic channel to ward off preventive military action. These nations preferred to develop nuclear capabilities in secret, but diplomacy afforded each the opportunity to transform a besieged nuclear pro- gram from a liability into a means of leverage. Indeed, a former spokesman for Tehran’s nuclear negotiating team claimed that Iran was pursuing a strategy of “turning threats into opportunities” by seeking to “obtain maximum concessions from their foreign counterparts in return for cooperation.”3

As this track record underscores, some US allies and even adversaries used offers to limit nuclear technology as a means to extract concessions when at the bargaining table with Washington. At other times, the threat of proliferation was not enough to coax US officials into complying with expensive demands, or even worse, generated dangerous and costly backlash. Given the wide spectrum of nuclear capabilities below the actual possession of nuclear weapons, when will a country be in the strongest position to extract concessions from the United States?

The central claim of this article is that there is an optimal range of nuclear technology for compellence because challengers are caught on the horns of a credibility dilemma. They must demonstrate sufficient resolve to cross the nuclear weapons threshold while also reassuring the target with costly signals that compliance will be rewarded with a nonproliferation commitment. The challenger’s level of latent capacity to produce nuclear weapons drives the severity of this tension between issuing credible threats and assurances. Moving closer to the bomb ratchets up threat credibility and the strength of the costly signals needed to convince the target to comply. The theory derives a series of specific claims about when the challenger will be in the best position with its nuclear program to resolve this dilemma and identifies the presence of a sweet spot between having too little and too much nuclear latency to extract coercive benefits. When a nuclear enterprise is in this middle zone, the challenger should be most able to reach an optimal bargain because the proliferation threat puts enough pressure on the target to comply, and the assurance costs of signaling strategic intent are low relative to the concessions reaped from the nuclear deal. An empirical effort to identify the lower and upper boundaries of the sweet spot in actual nuclear programs finds that it consistently reflects the ability to produce fissile material at enrichment and/or reprocessing (ENR) facilities across different US allies and adversaries over the last six decades.

This finding about the bargaining utility of nuclear latency overturns the conventional wisdom that nuclear weapons are a binary capability with uniform deterrent effects. Proliferation is not a dualistic outcome, “with states either having a fully-fledged arsenal or nothing at all. It spans a continuum” of latent nuclear capabilities, from countries struggling to operate uranium centrifuges to sophisticated programs with stockpiles of fissile material.4 Yet the literature “suffers from a considerable ‘existential bias,’ focusing almost entirely on a state’s quest for a nuclear weapons capability.”5 Aside from a few notable pioneers, “the existence of a tier of states technically capable of making weapons offering them significant military options in war and political leverage in peace is hardly noticed.”6 But the analytic focus is shifting down the capability spectrum as key countries in the Middle East and East Asia continue to retain nuclear latency in lieu of the bomb.7 This article joins an ongoing effort to understand the political implications of nuclear latency by explaining how “various thresholds in nuclear power technology” can be leveraged to practice compellence.8

The article is organized into four parts. The first crafts the logic of nuclear latency as an instrument of compellence, and derives hypotheses about the optimal extraction of coercive benefits. The second scopes out where the sweet spot might be in practice before devising a research design to select cases from the historical record. The third part studies episodes of compellence with nuclear latency to validate the theory and finds that the sweet spot is consistent over time and across challengers as different as South Korea, North Korea, and Japan. The conclusion situates these findings within the nuclear and crisis diplomacy literature, and explores the implications of the theory for US nonproliferation policy.

Read the full article in Security Studies


1. Leopoldo Nuti, “‘Me Too, Please’: Italy and the Politics of Nuclear Weapons, 1945–1975,” Diplomacy and Statecraft 4, no. 1 (1993): 137, 121.

2. US Department of State Cable 145139 to US Embassy India, “Non-Proliferation in South [Asia],” 6 June 1979, National Security Archive [hereafter NSA] Electronic Briefing Book 377.

3. Seyed Hossein Mousavian, The Iranian Nuclear Crisis: A Memoir (Washington, DC: Carnegie Endowment for International Peace, 2012), 99–100.

4. Austin Long, “Proliferation and Strategic Stability in the Middle East,” in Strategic Stability: Contending Interpretations, ed. Elbridge A. Colby and Michael S. Gerson (Carlisle, PA: US Army War College Press, 2013), 387.

5. Vipin Narang, Nuclear Strategy in the Modern Era: Regional Powers and International Conflict (Princeton, NJ: Princeton University Press, 2014), 299.

6. Brad Roberts, “VNAs and the Contemporary Latent Weapon State,” in Nuclear Weapons in a Transformed World: The Challenge of Virtual Nuclear Arsenals, ed. Michael J. Mazarr (New York: St. Martin’s Press, 1997), 264. For the classics on nuclear latency, see George H. Quester, “Some Conceptual Problems in Nuclear Proliferation,” American Political Science Review 66, no. 2 (June 1972): 490–97; Albert J. Wohlstetter, Swords from Plowshares: The Military Potential of Civilian Nuclear Energy (Chicago, IL: University of Chicago Press, 1979); Stephen M. Meyer, The Dynamics of Nuclear Proliferation (Chicago, IL: University of Chicago Press, 1986); Ariel E. Levite, “Never Say Never Again: Nuclear Reversal Revisited,” International Security 27, no. 3 (Winter 2002/03): 59–88.

7. Wyn Bowen and Matthew Moran, “Living with Nuclear Hedging: The Implications of Iran’s Nuclear Strategy,” International Affairs 91, no. 4 (July 2015): 687–707; Mark Fitzpatrick, Asia’s Latent Nuclear Powers: Japan, South Korea and Taiwan (London: Routledge, 2016); Vipin Narang, “Strategies of Nuclear Proliferation,” International Security (forthcoming).

8. Scott D. Sagan, “Nuclear Latency and Nuclear Proliferation,” in Forecasting Nuclear Proliferation in the 21st Century: Volume 1, The Role of Theory, eds. William C. Potter and Gaukhar Mukhatzhanova (Stanford, CA: Stanford Security Studies, 2010), 81. See also Matthew Fuhrmann and Benjamin Tkach, “Almost Nuclear: Introducing the Nuclear Latency Dataset,” Conflict Management and Peace Science 32, no. 4 (2015): 443–61; Gene Gerzhoy, Rupal Mehta, and Rachel Whitlark, “The Determinants of Nuclear Latency,” (paper presented at the 2016 Annual Conference of the International Studies Association, Atlanta, GA, 16–19 March 2016).