Research

From a historical perspective, presidents have frequently directed the use of military force without explicit permission from Congress. Yet, presidents still court legislative approval on select occasions. Why do presidents sometimes seek congressional authorization and other times do not? I explain authorization-seeking behavior according to variations in presidential bargaining strength. I argue that both weak and strong presidents prefer authorization-seeking; by obtaining congressional backing, weak presidents conceal a lack of national resolve from international audiences, while strong ones use approval to enhance their coercive authority. Presidents with mid-level bargaining strength, however, prefer unilateral action; on the one hand, unilateral action may demonstrate resolve in the face of potential legislative resistance, while on the other, it avoids contentious debate that risks “muddying” the diplomatic waters. I illustrate these arguments by revisiting four prominent historical cases: the Korean War, the Gulf of Tonkin crisis, the invasion of Cambodia, and the Persian Gulf War.

Why do states no longer declare war? In a provocative analysis, Tanisha M. Fazal argues that states stopped declaring war to evade the costs of complying with the growing body of international humanitarian laws. We argue instead that post-1945 normative and legal developments that sought to prohibit war changed the meaning of war declarations in a way that made them at best irrelevant and at worst counterproductive. Although war-making did not end, a once routine feature of warfare came to be seen as a signal of extreme aims that could complicate escalation management and coalition building. Moreover, the United Nations (UN) system provided more desirable ways for states to justify military operations, particularly through self-defense claims. We support this argument through a reassessment of the empirical pattern of war declarations, an analysis of self-defense claims made under Article 51 of the UN Charter, and case studies of undeclared wars in the post-1945 period.

Exchange Piece (with Tanisha Fazal and Kenneth Schultz): "The Decline in Declarations of War: An Exchange." Security Studies 30(5): pp. 893–904. 

What are the causes and consequences of military strategy? Whereas scholars traditionally emphasize the role of capabilities and geography in shaping strategic choices, I examine the social foundations of wartime conduct. I argue that warfighting norms constrain material calculations about military strategy, especially those made by the weakest actors in the international system. Changes in the strength or substance of these norms can systematically shape the way actors fight and, in turn, alter the outcomes of their wars. 

Using novel data on military capabilities, strategy, and international conflict, I show how battlefield restraint has evolved over time, with the normalization of guerrilla warfare by non-state actors and the promotion of brutal tactical substitutes by powerful states. I mobilize case evidence, ranging from the Iberian Peninsula to Southeast Asia, to demonstrate the social process of warfighting norms. Turning to conflict outcomes, I illuminate how the historical evolution in warfighting norms enabled weaker actors to survive longer when facing more powerful adversaries, thus drawing out asymmetric wars.

Together, my work produces several major findings in the study of war: first, that asymmetric wars have experienced substantially longer wars since 1918, while symmetric wars have not; second, that battlefield restraint has evolved over time; third, that mutually restrained warfare decreases conflict duration, while mutually unrestrained warfare increases it; and fourth, that norms against brutality have encouraged powerful states, especially liberal ones, to diversify their approaches to indiscriminate violence.

Do international norms against brutality constrain the use of indiscriminate violence by major powers in asymmetric conflicts? In theory, norms struggle to constrain major powers in asymmetric conflicts because weaker opponents have few options to retaliate, and third parties face high barriers to sanctioning major powers. I argue, however, that the norm against brutality has indirectly shaped the behavior of powerful states. The formation of injunctive norms, such as the norm against brutality, may lead states to alter their tactics, even as the overall strategy remains the same. In the case of indiscriminate violence during wartime, states respond to the norms by replicating the effects of the most extreme forms of the prohibited behavior via tactical substitution. Introducing new data on asymmetric war and reanalyzing existing data on colonial violence, I show that indiscriminate violence in asymmetric conflicts persists over time but has changed in its character since 1945. Powerful states wield the tools of indiscriminate violence in more indirect manners, with less complementarity, and at an adjusted magnitude. 

Why do intelligence analysts assign as much uncertainty to insurgents as they do great powers, despite receiving more resources to study the latter? In this paper, I establish this finding through an empirical analysis of the texts of 850 National Intelligence Estimates produced by the United States Intelligence Community between 1947 and 1991. I explain this phenomenon by developing a non-rationalist theory of uncertainty assessment grounded in the psychology of uncertainty and the psychology of power. I argue that U.S. intelligence analysts, as a consequence of a “superpower” mentality, systematically misplace certainty in their estimates about the United States’ least powerful adversaries, while inflating the uncertainty of their near peers. Using three different natural language processing (NLP) techniques, I explore the implications of this logic through further analysis of my corpus of NIEs. The paper challenges rationalist models of uncertainty assessment, which predict that more information leads to greater certainty about adversary intentions and capabilities. My findings reject that hypothesis and suggest that more resource allocation does not necessarily lead to improved analytical products.

Since the early twentieth century, asymmetric wars—wars between strong and weak powers—have grown in length, while symmetric wars—wars between similarly capable powers—have not. What explains the divergence in the duration of asymmetric and symmetric wars? I argue that changing beliefs about guerrilla warfare facilitated this phenomenon. Although weaker war participants have relied upon guerrilla warfare throughout world history, the strategy’s prevalence dramatically grew during the early twentieth century, as normative developments destigmatized its use. Critically, the globalization of guerrilla warfare as the preferred strategy of the weak introduced additional information problems in asymmetric wars, which contributed to longer war durations. I examine this argument, alongside alternatives about rebel endowments and coercive norms, through an exploration of extra-, intra-, and inter-state wars from 1816 to 2006.

Recipient of Best Graduate Paper in Scientific Studies of International Processes, ISA 2024.

Counterinsurgency campaigns led by foreign powers are often wrought with successive failures to adapt to threats posed by non-state adversaries. Why do policymakers face barriers to learning in counterinsurgency? I introduce a new theory of counterinsurgent learning that emphasizes the tightness of social norms in national security organizations. Changes in the strength of social norms, specifically those related to conformity and deference to authority, impact learning by shaping the sharpness of insurgent signals and the weight of prior beliefs about an insurgent threat. Relying upon recently declassified documents, I process trace these mechanisms, as well as alternative ones on rebel technology and force structure, through a case study of the U.S. war in Afghanistan. I also test key hypotheses with cross-national data on wars of counterinsurgency. This research has implications for the literature on organizational learning, threat assessment, and counterinsurgency.

How do state officials evaluate the risk of international terrorism and insurgency? Existing explanations predict that state officials rely on observable behaviors of strength to guide threat assessments, but these indicators often serve as poor proxies of prospective capabilities and produce noisy signals instead. We develop an alternative argument that -- under large amounts of uncertainty -- officials evaluate the risk of future violence through the construction and application of a threat schema. We identify two factors governing the construction of these schema: retrievability of comparable cases and information processing techniques. We examine our theory through a case study of the 1979 Herat Rebellion in Afghanistan, where Soviet and American officials reached opposing conclusions about the conict's prospective trajectory despite possessing similar information. Our findings advance understanding about foreign policy decision-making and threat assessment for terrorism and insurgency.