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HOME > REGIONS > Asia, Pacific Rim      
The American Security Case for Seoul and Tokyo Not Going Nuclear


In the midst of deteriorating security relations between Seoul and Tokyo, Japanese Prime Minister Shinzō Abe recently announced Japan was terminating its joint deployment of a land-based U.S. missile defense system, AEGIS Ashore. Meanwhile, Washington continues to lean on Japan and South Korea to pay billions more for the continued basing of American military forces in each country.

It’s unclear how this story will end. One ending has Japan and Tokyo going nuclear and relying less on the U.S.. This option privately has backers in Washington, Tokyo, and Seoul. As the attached NPEC-commissioned study by Eric Heginbotham and Richard J. Samuels of MIT make clear, however, it’s less than a bad option; it’s dead wrong. As they note:

Neither new allies [e.g., Australia, India, and South Korea] nor nuclear weapons would empower these states to balance Chinese power more broadly. Indeed, they might instead be accompanied by greater accommodation.

This, in turn, would only increase the risk of Tokyo and Seoul parting ways with Washington or, worse, catalyzing East Asian tensions and war. Heginbotham and Samuels want none of this. Their study makes for useful reading as do their recommendations to adjust how our military works with Japan and South Korea on nuclear and other deterrence matters.

Jul 23, 2020
AUTHOR: Eric Heginbotham and Richard J. Samuels
Eric Heginbotham and Richard J. Samuels Paper (PDF) 553.08 KB

Vulnerable Alliances: U.S. Unpredictability and the Search for a “Plan B” in South Korea and Japan*

Eric Heginbotham and Richard J. Samuels
Center for International Studies
Massachusetts Institute of Technology
June 2020

For decades, scholars and practitioners of international relations have been predicting that China’s rise would prompt energetic balancing behavior by Asia’s “middle powers,” including a reconciled Japan and South Korea.1 As one confident U.S. military officer told us in 2017, “Japan-ROK historical enmity will dissolve when self-interest kicks in.”2 That this has not come to pass is attributed to various factors: Realists note the incentives for states to “buck pass” or to “cheap ride,” i.e., to follow the logic of moral hazard by which U.S. security guarantees obviate the need for its allies to balance. Arguing that Washington bears a disproportionate share of the burden for maintaining security and stability in East Asia, they suggest that the United States step back and force its allies to step forward. This argument has found a receptive audience among those who would prefer to rebuild at home, rather than buttress alliances overseas.3 

Observing that bilateral relations between Seoul and Tokyo remain unsteady and that balancing and free riding have been uneven, other scholars suggest that Northeast Asian international relations may follow principles shaped by the inertia of institutions, by ideas, by leaders, and by history.4 While non-material factors matter, they cannot adequately explain regional dynamics on their own. Predictions of cultural change stimulating reconciliation, like putative realist predictions of allied convergence, undervalue the different security conditions constraining America and its allies. Although Washington, Tokyo, and Seoul all confront a rising China, the material and ideational circumstances under which they do so vary; each faces different problems and considers different options in a different context as it contemplates how best to pursue security.

We examine the security problems facing Japan, the Republic of Korea (ROK), and the United States, the extent to which their national interests converge, and the differential impact of external and domestic change on extant alignments. Rather than rely on material or ideational factors alone, we demonstrate how practitioners and strategists in each country debate different means of addressing challenges, and how their debates—shaped primarily by external circumstances, but deeply affected by a wide array of historical, ideational, and structural factors—may affect U.S. strategy.5

We find that the degree and nature of threats faced by both Japan and Korea have changed markedly over the last decade, but note how the dilemmas facing the ROK are more severe and limiting. We also examine how these circumstances and perspectives feature in debates in Tokyo and Seoul about how best to respond to the oscillations and unpredictability of American foreign policy, the “900 pound gorilla” with the potential to further upend their security calculations.

Washington’s Northeast Asian allies are actively considering what sort of “Plan B” might be crafted to offset the impact of diminished alliance with the United States, and the available options are not entirely appealing – either for them or for the United States. In Seoul, these include an increasingly serious consideration of nuclear options, which could prompt Tokyo to follow suit. In Tokyo, the first options include experimenting with a new regional security architecture while hedging against U.S. abandonment. U.S. allies’ options should not, however, be equated with “stepping up” or “doing more.” Neither new allies nor nuclear weapons would empower these states to balance Chinese power more broadly. Indeed, they might instead be accompanied by greater accommodation.

Given this landscape and the potential for further misalignment, we conclude that remaining engaged as an active security partner is still Washington’s best option. Pushing U.S. allies to increase their financial support for U.S. forward deployed forces – by threatening withdrawal is likely to backfire. Such threats, if they work at all, will likely encourage allies to hedge against uncertainty by reproducing capabilities supplied by the United States, rather than produce a more rational division of labor.


* The authors gratefully acknowledge the support for this research provided by the Nonproliferation Policy Education Center.
1 See, for example, Richard L. Armitage et al., “The United States and Japan: Advancing toward a Mature Partnership, INSS Special Report, October 11, 2000; Jason U. Manosevitz, “Japan and South Korea: Security Relations Reach Adolescence,” Asian Survey, September/October 2003.
2 Interview, November 14, 2017, Camp Zama. This prediction was first cited in Eric Heginbotham and Richard J. Samuels, “With Friends Like These: Japan-ROK Cooperation and U.S. Policy,” The Asan Forum, March - April 2018 Vol.6, No.2.
3 Thomas J. Christensen and Jack Snyder. “Chain Gangs and Passed Bucks: Predicting Alliance Patterns in Multipolarity,” International Organization, V.44, No.2, Spring, 1990, pp.137-168; Eugene Gholz, Harvey Sapolsky, and Daryl Press. “Come Home America: The Strategy of Restraint in the face of Temptation,”
International Security, V.21, No.4, Spring 1993, pp.5-48; Barry Posen. Restraint: A New Foundation for U.S.
Grand Strategy. Ithaca: Cornell University Press, 2014.
4 For a recent historical-institutional analysis of Asia’s security architecture, see Andrew Yeo, Asia’s Regional Architecture: Alliances and Institutions in the Pacific Century. Stanford: Stanford University Press, 2019. For more on how politicians in Japan and South Korea confound efforts to reconcile, see Jennifer Lind. Sorry States: Apologies in International Politics. Ithaca: Cornell University Press, 2008. For a Japan and the DPJ Government,” chapter 7 in T.J. Pempel and Chung Min Lee, eds. Security Cooperation in Northeast Asia: Architecture and Beyond. London: Routledge, 2012.
5 This approach is often labeled “neo-classical realism” and is elaborated in Steven E. Lobell, et al., eds. Neoclassical Realism, the State, and Foreign Policy. Cambridge, UK: Cambridge University Press, 2009.

To read the entire paper, click here.

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