States accused of perpetrating cyber operations typically do not confirm or deny responsibility. They issue ‘non-denial denials’ or refuse to comment on the accusations. These ambiguous signals are prevalent, but they are largely ignored in the existing cyber literature, which tends to treat credit claiming as a binary choice. The ambiguity of non-denial denials and ‘non-comments’ allows states to accomplish two seemingly opposed goals: maintaining crisis stability and leaving open the possibility of their involvement in the attack. By deliberately remaining a suspect, a state can manipulate rivals’ perceptions of its cyber capability and resolve. Refusing to deny responsibility can also shape rivals’ perceptions of allies’ capabilities, enhancing the credibility of deterrence. All of this can be accomplished without the escalatory risks that would come with an explicit admission of responsibility. Where previous research has focused on the dangers of escalation and the limitations of costly signalling with cyber, we show that non-denial denials and non-comments make cyber operations considerably more useful than the literature appreciates.

The question of where to begin when considering the conditions under which states and non-state actors comply with international humanitarian law (IHL) is itself an interesting one because of the history of IHL. IHL was created by states, principally to govern their behavior in relation to each other. The major codified elements of IHL, such as the 1949 Geneva Conventions, are agreements signed by states. For the last several decades, however, most wars have occurred within, rather than between, states. This trend raises the question of whether and when armed non-state actors (ANSAs, typically called “rebel groups” by political scientists) might comply with IHL.

One likely effect of the COVID-19 pandemic will be an increased focus on health diplomacy, a topic that has rarely been taken up by international relations scholars. After reviewing existing literature on health diplomacy, I argue for the utility of distinguishing states’ aims from their practices of health diplomacy in advancing our understanding of when states engage in health diplomacy with a bilateral, regional, or global scope. The recent history of twenty-first century infectious disease outbreaks suggests a possible move away from health diplomacy with global participation. COVID-19 provides numerous examples, from widespread criticism of the World Health Organization to increased bilateral health aid and the creation of a regional vaccine initiative. As pandemics become more frequent, however, more localized health diplomacy is likely to be less effective, given the necessity of global mitigation and containment.

What will be the consequences of the criminalization of aggression? In 2010, the International Criminal Court made aggression a crime for which individuals can be prosecuted. But questions around what constitutes aggression, who decides, and, most important, how effective this legal change will be in reducing the incidence of war remain. This essay considers these questions in light of two recent books on the criminalization of aggression: Noah Weisbord's The Crime of Aggression: The Quest for Justice in an Age of Drones, Cyberattacks, Insurgents, and Autocrats and Tom Dannenbaum's The Crime of Aggression, Humanity, and the Soldier. While the authors argue in favor of the efficacy of the criminalization of aggression as a means to reduce future war, it is also likely that the criminalization of aggression will reshape war in potentially profound ways.

When the United States terminated its seven-year occupation of Japan in 1954, it did so having signed a peace treaty. By contrast, the United States tried, unsuccessfully, to persuade Hamid Karzai to sign a Bilateral Security Agreement to accompany the drawdown of U.S. forces in Afghanistan. Even if Karzai had agreed to sign, the draft agreement bears much stronger resemblance to an alliance than to a peace treaty; it does not reference hostilities between the United States and Afghanistan, nor does it include any version of the term “peace treaty.”

Recent scholarship has found identity variables to be insignificant predictors of civilian targeting in war. Drawing on the European origins of the law of war, this article argues that previous scholarship has neglected the one specification of ‘identity’ that is most theoretically justified for understanding civilian targeting: whether a European state is fighting a non-European state. This article replicates and extends three recent statistical analyses – Downes; Valentino, Huth and Croco; and Morrow – of civilian targeting by including a variable capturing whether a European state fought a non-European state. The study finds that civilian targeting, and non compliance with the law of war more generally, is significantly more likely in European v. non-European dyads than in other types of dyads.

The conclusion of peace treaties following war was a norm of international politics for millennia. Since approximately 1950, however, the rate at which interstate wars have ended with a formal peace treaty has declined dramatically. I argue that the costs of concluding peace treaties have risen with the development of the modern canon of the law of war. Using an original data set, I find that states today prefer to avoid admitting to a state of war and risk placing their leaders and soldiers at risk of punishment for any violations of the law of war.

Under what conditions do states die? Survival is often assumed to be the primary goal of states. Yet international relations scholars have not previously examined the rate or the causes of state death in a systematic way. I argue that buffer states—states caught between two rivals—are particularly vulnerable to being coerced out of existence. Each rival is afraid that its opponent will conquer the buffer that lies between them, gaining strength and strategic advantage. The rivals' inability to credibly commit to preserving the buffer state's sovereignty means that buffer states are extremely vulnerable to conquest. Using event history analysis, I test this argument while controlling for traditional realist variables such as power and alliances, as well as for changes in the post–World War II era. The analysis generates three major findings: buffer states are significantly more likely to die than are nonbuffer states; violent state death (conquest and occupation) virtually ceases after 1945; and the relationship between power and state survival is tenuous.For their valuable comments and suggestions, I thank James Fearon, Page Fortna, Erik Gartzke, Hein Goemans, Simon Jackman, Stephen Krasner, David Lewis, Scott Sagan, Erik Voeten, the editor of IO, two anonymous reviewers, as well as seminar participants at Stanford University, Harvard University, the University of Chicago, and the University of Virginia Law School. Earlier versions of this article were presented at the 2000 Annual Meetings of the International Studies Association and the American Political Science Association. Jessica Stanton provided valuable research assistance. I gratefully acknowledge the support of the Center for International Security and Cooperation and the John M. Olin Institute for Strategic Studies. Any errors are my own.