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Hulme, M Patrick, and Erik Gartzke. 2021. “The Tyranny of Distance: Assessing and Explaining the Apparent Decline in U.S. Military Performance.” International Studies Quarterly 65(2): 542–50. (link)

There is a growing sense that U.S. military effectiveness has been on the wane in recent years.  Is this the case? If so, what are the reasons for the decay in American combat performance?  We first examine the available systematic evidence for American military decline, showing that the United States has indeed experienced a drop in the quality of outcomes of its military contests. Observers have offered a number of explanations for declining American military success, most predominantly  an increase in intrastate conflict after the Second World War. After showing that a decline in performance is observed even after fully excluding intrastate conflict, we propose an alternative explanation: the increasing distance-from-home at which the United States has been fighting. Distance is tyrannical: it saps military strength and increases the cost of contests, even as it reduces U.S. expertise and motivations to prevail. We then show that the distance from home at which the United States fights is the best predictor of the outcome of the conflict. We conclude by noting some avenues for future research and policy implications as the world returns to great power competition.

Power, Parity and Proximity (with Erik Gartzke, Lauren Gilbert and Alex Baithwaite)
(Revise and Resubmit at
International Studies Quarterly)

Research debating competing perspectives on power and war has yet to address the endogenous impact of proximity. If power declines in distance, then power relations between two nations differ at different points on the globe. Claims about the impact of parity or preponderance on conflict and peace then really only apply to particular points or regions in the space separating borders or national capitals. We use a formal bargaining model to demonstrate that dyads should be most prone to fight in places where each state’s capabilities, discounted by distance, are roughly at parity. We then assess this relationship empirically, introducing the directed dyad year location unit-of-analysis to capture the impact of geographic distance on power and the propensity to fight. Results confirm that disputes are most likely at locations where the distance-weighted capabilities of nations are roughly equal.

Appetite Suppressant: Nuclear Weapons, the Rise of Limited War, and the Decline of Declarations of War 

Declarations of war used to be a common occurrence in international conflict, but are now very rare. Recent research in political science has sought to explain this observed change in behavior. Fazal argues that the proliferation in international covenants regulating armed conflict created an incentive for states to avoid compliance costs by not formally recognizing a state of war. Irajpanah and Schultz argue, instead, that the meaning of war declarations changed after 1945 due to the U.N. Charter, and came to be seen as inherently aggressive—a signal states sought to avoid sending. This paper proposes an alternative explanation: declarations of war didn’t change—the nature of war did. War declarations under traditional international law were a formal recognition of a state of war—i.e., “general war”: war unlimited in means or geographic scope—between sovereign states. The number of conflicts that would actually meet these rather stringent criteria post-1945 is actually quite small, however. Rather than declarations of war having a new meaning after 1945, this article points out that the nature of armed conflict itself changed after World War II. Technological advances such as nuclear weapons made general war much less palatable, and limited war more attractive—thus simply rendering declarations of war less applicable in the postwar era. 


The Taiwan Question in U.S. Grand Strategy (with James Lee) (draft)

The Taiwan Question is one of the most important policy issues facing the United States today. On the one hand, twenty-five million free individuals in a thriving liberal democracy--and the world’s most important semiconductor manufacturing hub--hang in the balance. On the other hand, committing to defend the island would entail the United States running the risk of a major crisis, and perhaps even war, unseen in over half a century. Accordingly, a lively policy debate has grown in prominence over the past year as to whether the United States should reconsider its current policy of “strategic ambiguity” toward the island. Alternative policy options include, on one extreme, “strategic clarity” (i.e., making a formal policy commitment to defend the island) and, on the other extreme, renunciation (i.e., disclaiming any intent to do so). Much of this debate, however, has been limited to Taiwan and China specialists familiar with the intricacies of U.S. policy toward the island. Given the enormous stakes involved, it is imperative that such a conversation over Taiwan policy be placed within an overarching framework of what U.S. national interests are and how to best achieve those ends: grand strategy. To this end, this paper outlines five ideal-type grand strategies--Liberal Internationalism, Deep Engagement, Conservative Primacy, Offshore Balancing, and Restraint--and attempts to distill each strategy’s policy prescription for the U.S. relationship with Taiwan.

Congress, Crisis, and the Constitution in the Taiwan Strait (draft)

Recent worries of a full-scale crisis over Taiwan have raised questions of what role---if any---Congress would have in a hypothetical Sino-American confrontation over the island. Indeed, calls to move from a declared policy of "strategic ambiguity" to "strategic clarity" have yet to fully address how much ambiguity would actually be resolved if Congress were not part of this revision. This article first lays out a novel theory of how Congress has mattered in international crises since the end of the Second World War, despite a widespread belief in an "Imperial Presidency". Crucially, the theory implies presidents will be highly averse to actually utilizing significant American military force absent congressional backing. U.S. adversaries, furthermore, realize this and consequently partially base their assessments of American resolve on the sentiment they observe emanating from Congress. It then illustrates the logic of the theory through a close examination of American and Chinese decision-making during the First Taiwan Strait Crisis in 1954-55. The paper then closes with a consideration of implications for other crises, including in the Taiwan Strait today.

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