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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)
(Under Review

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.

War and Responsibility: Executive Constraint Overlooked

In the context of the war powers, it is widely believed that the United States has a little-constrained “imperial presidency”. Congress avoids going “on the record” on matters of war and peace, and American presidents de facto have virtually unlimited discretion over use of military force decisions. Overlooked, however, is that with great power comes great responsibility. American combat deaths in less-than-successful military ventures expose presidents to political costs more easily levied on an executive that acts absent sufficient political cover from lawmakers. Taking account of these Loss Responsibility Costs, this article shows that the United States actually has an executive substantially constrained by Congress.

A model of the war powers factoring in these costs in a crisis bargaining game is introduced, and two principal results are highlighted. First, while smaller uses of force are undertaken unilaterally, the largest uses of force (i.e., full scale wars) are only undertaken subject to formal authorization from Congress. Second, exposure to these costs constrains presidential behavior even in the context of smaller uses of force undertaken unilaterally. Empirical evidence supporting both propositions is then provided. Novel data gathering sentiment from congressional floor speeches in nearly two hundred crises shows that, far from having an imperial presidency, congressional sentiment appears to operate as a necessary condition in degree for the scale of force utilized by the White House.

Coercion, the Constitution, and the Search for Credibility

American politicians have for decades perceived a link between coercive credibility and the question of the constitutional war powers of Congress and the president. For example, the two largest blunders in American foreign policy since 1945—the Vietnam and Iraq Wars—were both preceded by votes in Congress in which many lawmakers argued voting in favor of war would make war less likely. Yet, despite the dire consequences of such formal authorization for the use of military force by Congress, precious little attention has been given by political scientists as to how the war powers and coercion actually interact.

This article first outlines the coercive logic of congressional authorizations for the use of military force (AUMFs) though a series of formal models. The key intuition shown is the effect is not purely informational, as prior models of domestic politics might suggest. Instead, formal authorization serves a functional role as an “incentives-rearranging” type mechanism, making intervention—and intervention at a higher scale—much more likely and thus credible. At the same time, the act of seeking authorization can, under certain circumstances, expose a president as a weak type and undermine threat credibility in the long run. While presidents benefit greatly from the political cover of formal authorization, they therefore resist appearing too eager for the backing of the legislature; presidents are careful to cultivate and maintain an image of an imperial presidency.

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