[Home] [CV] [Data] [Teaching] [Personal]

My principle research agenda is the social scientific study on the role of diplomacy and its institutions in international disputes and conflict resolution. I have a series of projects to develop and test theories that identify several specific mechanisms of diplomacy and explain when and why each mechanism facilitates (or sometimes hinders) conflict prevention and resolution short of war. The second line of research is theoretical analysis of the origins of war and peace, which consists of several loosely interrelated projects on the issues of audience costs, perception and misperception in a signaling and communication context, and credibility among others.

Research statement (pdf) – outdated

Published Papers


Signaling and Perception in International Crises: Two Approaches
Journal of Theoretical Politics, 28(4), 625-654, Fall 2016.

      DOI: 10.1177/0951629815603492

[Supplementary Material] [Poster (pdf)]

This study contrasts the rationalist and psychologist approaches to information failure as the cause of crisis escalation and war. Building on the psychological insights on misperception, I study a simple game-theoretic model of crisis bargaining, where signals are subject to perceptual errors and thereby multiple interpretations. The model allows us to analyze the interplay between the strategic problem of misrepresentation in sending signals and the problem of misperception in forming beliefs. The analysis offers a rationalist logic of signaling and perception, which links Bayesian learning, incentive problems, misperception, and war. The analysis also shows that misperception generates more than pathologies in crises---misperception, under the right condition, makes signals fully informative, reduces the risk of war, and attenuates the adverse impact of incomplete information on the risk of crisis escalation and war.


A Signaling Game of Collective Self-Defense in the U.S.-Japan Alliance
Games of International Conflict and Cooperation in Asia, edited by Motoshi Suzuki and Akira Okada, Springer, forthcoming

[Slides (pdf)]

What are the implications of collective self-defense for Japan's security environment?  This chapter considers invoking the right of collective self-defense as intervention into an armed conflict on behalf of an ally.  Since the Japanese government's reinterpretation of the constitutional constraint on collective self-defense is perceived by neighboring countries as a revelation of underlying militarism and expansionism, I analyze Japan's decision on its constitutional constraints as a costly signal that Japan sends to deter the challenges against the U.S.-Japan alliance.  The equilibrium analysis suggests that the manipulation of collective self-defense does not help Prime Minister Abe and his government achieve the security policy objectives that they claim invoking collective self-defense would deliver.

Japan’s Changing Defense Posture and Its Implications for Security Relations in East Asia (with Andrew Capistrano)

Korean Journal of International Studies, 14 (1), April, 2016, pp. 77-104.

     DOI: 10.14731/kjis.2016.

Japan’s Diet passed new defense legislation in 2015. It reinterprets the constitutional clause renouncing the threat or use of force (except to repel an attack on Japan) to allow collective self-defense and permit expanded roles for the Japanese Self-Defense Forces. The government presents these changes as consistent with Japan’s traditional postwar defense posture, vital to support allied deterrence of threats against Japan, and necessary to enhance Japan’s security in a region of shifting power. This article disputes these claims. Rather, the new laws (1) signal a strategic shift away from the Yoshida Doctrine by reinterpreting the constitution, (2) fail to generate new U.S. commitments or strengthen preexisting ones that enhance Japan’s security, and (3) risk exacerbating the Sino-Japanese security dilemma. This is because the changes are occurring alongside the Senkaku Islands dispute, which raises strategic mistrust, and they revise the alliance to give Japan a greater role in regional security, which China has historically seen as a future threat. When taken together, these under appreciated effects of the new laws may help the alliance endure and let Japan support the regional status quo in the long term, but will likely decrease Japanese security in the short term by prompting a defensive Chinese response. We show how the recent history of East Asia’s security dilemma and IR theory both cast doubt on the ability of the new laws to generate security for Japan.


Detecting Audience Costs in International Disputes (with Taehee Whang)
International Organization,
69 (4), Fall 2015, pp. 949-980.

[Supplementary material] [Slides (pdf)] [Replication material]

      DOI: 10.1017/S0020818315000211

We present observational evidence of audience costs. Selection effects in crisis bargaining make it difficult to directly observe audience costs because when state leaders anticipate larger audience costs they attempt to avoid incurring them. We use a structural statistical model to estimate the size of audience costs, both incurred and not incurred, in international crises. We show that while audience costs exist for state leaders of various regime types, democratic leaders face larger audience costs than nondemocratic leaders do. Audience costs can be so large that war might be preferable to concessions especially for leaders of highly democratic states. Audience costs also increase a state's bargaining leverage in crises because the target state is more likely to acquiesce if the challenge carries larger audience costs. We also find evidence that audience costs generate selection effects. These results establish an empirical foundation for audience costs propositions.

Efficient Secrecy: Public versus Private Threats in Crisis Diplomacy
American Political Science Review, 101, 3 (August 2007), pp. 543-558.

[Supplementary Material (pdf)] [Erratum (pdf)] [Poster (pdf)]

DOI: 10.1017/S0003055407070396

This paper explores when and why private communication works in crisis diplomacy. Conventional audience-cost models suggest that state leaders must go public to reveal information in interstate crises because leaders cannot enhance their credibility by tying their hands if domestic audiences cannot observe their private signals. I present a crisis bargaining game where both the sender and the receiver of signals have a domestic audience. The equilibrium analysis demonstrates that a private threat, albeit of limited credibility, can be equally compelling as a fully credible public threat. Secrecy works in crisis diplomacy despite its informational inefficacy because secrecy insulates leaders from domestic political consequences when they capitulate to a challenge to avoid risking unwarranted war. The logic of efficient secrecy may shed light on the unaccounted history of private diplomacy in international crises. The Alaska Boundary Dispute illustrates this logic.


Dyadic Effects of Democratization on International Disputes: Theory and Evidence
International Relations of the Asia-Pacific, 4, 1 (February 2004), 1-33

[Replication data]

DOI: 10.1093/irap/4.1.1

I explore the dyadic, as opposed to monadic, effect of democratization on war. Using a simple repeated game of interstate interaction, I show that, as a state shifts toward democracy, the public obtains more opportunities and becomea more willing to remove the leaders who are expected to reduce their future welfare. Anticipating this consequence, rational leaders’ incentives to avoid breaking the cooperative relationship with democracies grow stronger as a state becomes democratic. The hypothesis drawn from the model anticipates that democratization has a pacifying effect in the dyadic relationship with democracies. Empirical testing is designed to isolate the dyadic effect from the monadic one and to distinguish among competing hypotheses. The expectations are tested using widely employed data on political institutions and militarized interstate disputes. The result shows that democratization reduces the likelihood of waging war when the opposing state is democratic, while the risk of war remains unchanged when facing a non-democratic opponent.


Working Papers


Diplomacy, Pre-crisis Communication, and War

[Supplementary Material] [Slides (pdf)] [Replication data] [Replication codes]*

Diplomacy is a primary form of politics among nations and offers a set of institutions and norms to facilitate credible communication and conflict resolution. Previous research, however, suggests that diplomacy is not effective at communicating messages and does not mitigate the risk of war. Generalizing previous models of repeated crises with cheap-talk, I challenge these results by describing how two processes of diplomacy---communication and representation---bind together to form diplomatic institutions as equilibria. In these equilibria, diplomacy can convey information more effectively than previously suggested. And yet, diplomacy, if informative, can simultaneously increase and reduce the net risk of war, depending on the strategic environment. The statistical analysis of original data on diplomatic channels supplements the theoretical ambiguity, showing that diplomacy reduces the risk of armed conflict by twenty percent. These results refine the logic of diplomatic communication and redefine its significance as an instrument of statecraft.
* available upon publication


Democracy, Information, and Audience Costs (with Taehee Whang)

[Supplementary Material][Slides (pdf)][Replication data] [Replication codes]*

The audience cost models posit that audience costs help democratic leaders better signal their resolve to the adversary and thus more likely to prevail in crises. A large volume of empirical work turn to this ``informational'' conjecture about audience costs to explain the association between domestic political institutions and crisis behavior. Although many indirect tests exist, none has yet delivered definitive evidence. We present direct evidence that quantifies the amount of learning through structural estimation of a standard crisis game with audience costs. Our estimation demonstrates that the higher is the estimated level of audience costs faced by a threatener, the more convinced is the adversary that the threatener is resolve to use force in a crisis. We also find that our estimated informational effect of audience costs is statistically significant. Our results, thus, provide an empirical foundation for the ``informational'' account of the audience costs mechanism in international crises.


Inferring Secret Diplomacy (with Taehee Whang)
To be submitted

[Supplementary Material][Slides (pdf)][Replication data] [Replication codes]*

Inferring secret diplomacy is challenging because it is not systematically observable. We offer two types of evidence for a theory that explains when and why a private challenge works in international crises. First, secret diplomacy works because it insulates the acquiescing leaders from political costs for making concessions. Secrecy would play no role in international crises if state leaders are insensitive to political or diplomatic defeat in public. To test this necessary condition as a falsifiable hypothesis, we use the structural approach to estimate the underlying payoffs for states in international crises. Second, when secret diplomacy works, the acquiescing state must believe that the challenger is *less* resolved to fight when receiving secretive challenges. Because successful secret diplomacy is observationally equivalent to the status quo in the eyes of analysts, we expect the negative shift in the target's belief on the challenger's resolve when the status quo is observed. Our analysis finds support for both hypotheses.


Threats and Assurances in Coercive Diplomacy (with Atsushi Ishida)

[Supplementary Material] [Slides]

A threat to punish for noncompliance must imply a promise not to punish for compliance. I formalize this problem of assurances in a simple model of coercive diplomacy in which a threat of force also implies the assurance of security after concessions. Facing dual goals of communicating resolve and reducing the fear of attack after concessions, the challenger must weigh the credibility of threats against the credibility of assurances. The target's dilemma is to balance dual risks: the risk of a costly conflict after resisting the threat; and the risk of attack after concessions shift the military balance. The analysis establishes the sufficient conditions for an equilibrium in which assurances are always guaranteed and an equilibrium in which assurances are never feasible, and shows that the lack of assurance undermines coercive diplomacy. I also explore if credible assurances can undermine the credibility of threats and vice versa.


Works in Progress

When Diplomacy Works, (book manuscript in progress)
[Chapter outline][Book proposal] (Extended version)


Bringing Diplomacy Back In
To be submitted

This essay offers theoretical motivation and foundations for the scientific study of diplomacy in international disputes. First, it demonstrates that the academic interest in diplomacy has declined in parallel to the evolution of strategic thoughts and nuclear strategies during the Cold War. Second, using a simple bargaining model of crisis bargaining, I show that understanding diplomacy is crucial for the better understanding of the rationalist puzzle of inefficient wars because the existing rationalist explanations bring us back to the original puzzle. Third, I argue that a successful theoretical foundation must bring together three previously divergent literatures: the rationalist approach, the English School, and the diplomatic studies. I propose three general mechanisms of diplomacy and suggest that each of these mechanisms provides a basis for an empirically identifiable mechanism of diplomacy in international disputes. Diplomacy can be a new addition to the ``Correlates of War'' and its role can be understood in the same way as war and military coercion.


Diplomatic Negotiation and Military Coercion in International Disputes
In progress
[Supplementary Material]

I study a model of diplomatic negotiation, where bargainers take turns deciding whether to continue diplomacy or resort to coercion. Departing from previous models, military outside options are subgames where bargainers play a costly signaling game, rather than the game-ending war lottery. Hence, bargainers can engage in both bargaining through diplomacy and signaling through military coercion. I show that countries with “weakerbargaining power have an incentive to opt out from diplomacy to send costly signals through military coercion to gamble for a greater bargain. This is because military coercion carries more information than diplomatic bargaining, suggesting that the rationality of diplomacy does not rely on its informational efficacy. Hence, powerful countries with “strongerbargaining power are less likely to run the risk of military coercion. The analysis shows that the conventional rationalist account of war cannot adequately explain why some international disputes are settled by diplomatic negotiations. The logic of success or failure of diplomatic negotiation is at the core of our understanding of the origins of war and peace.


Diplomatic Relations in International Politics (with Kelly Matush)
In progress
[Supplementary Material] [Replication data]*

This paper presents a first cut at testing theories and common conjectures about diplomatic statecraft and its machinery. To do so, we identify the determinants of diplomatic interactions and their breakdown through a series of Markov probit regressions on bilateral diplomatic relations, using the newly collected annual data sets on diplomatic representations for the past two centuries. We delineate how various political, economic, and military factors characterize the so-called European system of diplomacy in the 19th century and the American system in the 20th century, and explore the extent to which the two systems differ from each other. These estimated systems of diplomacy offer empirical diplomatic theory. Our theory illuminates the patterns of diplomatic statecraft and its relationship to other key dimensions of international relations. It also refutes some of common beliefs about diplomacy. For example, while military conflict almost always impedes diplomatic relations of in the American system, it tends to facilitate diplomatic exchanges in the European system. Political ideology or regime type has no impact on diplomatic relations in the European system, while the relationship between political ideology and American diplomatic statecraft changes drastically, depending on the political and strategic characteristics of the other countries.
* available upon publication


Strategic Affinity with the U.S. and Transnational Terrorism (with Mina Watanabe and Ryuya Koishi)
In progress

The Diplomacy of Apology (Hiroyuki Fukushima)
In progress

The Case for Democratic Credibility (with Piotr Urbanski)
In progress