This essay assesses the morality of Ukraine's use of drones to attack targets inside Russia. Following its invasion by Russian forces, Ukraine has had a just cause to wage a war of self-defense. However, its efforts to achieve that cause remain subject to moral limits. Even a state that has been unjustly attacked may not, for example, respond by deliberately targeting the attacking state's civilian population. To do so would violate the jus in bello principle of discrimination. The essay first describes how drone technology has frequently enabled long-range strikes against Russian military assets as well as other targets inside cities. It then explains why it would be morally wrong for Ukraine to attack its enemy's population centers. First, Russian civilians are not liable to attack, and this nonliability is undiminished by the injustice of Russia's invasion or by any in bello wrongs committed by the Russian military. Second, attacking Russian cities with drones would arguably achieve little or no self-defensive benefit for Ukraine, and it could even be counterproductive.

Traditional just war doctrine holds that political leaders are morally responsible for the decision to initiate war, while individual soldiers should be judged solely by their conduct in war. According to this view, soldiers fighting in an unjust war of aggression and soldiers on the opposing side seeking to defend their country are morally equal as long as each obeys the rules of combat. Revisionist scholars, however, maintain that soldiers who fight for an unjust cause bear at least some responsibility for advancing an immoral end, even if they otherwise fight ethically. This article examines the attitudes of the American public regarding the moral equality of combatants. Utilizing an original survey experiment, we find that the public's moral reasoning is generally more consistent with that of the revisionists than with traditional just war theory. Americans in our study judged soldiers who participate in unjust wars as less ethical than soldiers in just wars, even when their battlefield conduct is identical, and a large proportion supported harsh punishments for soldiers simply for participating in unjust wars. We also find, however, that much of the American public is willing to extend the moral license of just cause significantly further than revisionist scholars advocate: half of the Americans in our survey were willing to allow an unambiguous war crime—a massacre of innocent women and children—to go unpunished when the act was committed by soldiers fighting for a just cause. Our findings suggest that incorporation of revisionist principles into the laws of war would reinforce dangerous moral intuitions encouraging the killing of civilians.

Threats of armed force are frequently employed in international affairs, yet they have received little ethical scrutiny in their own right. This article addresses that deficit by examining how threats, taken as a speech act, require a moral assessment that is distinctive vis-à-vis the actual use of armed force. This is done first by classifying threats within the framework of speech act theory. Then, applying standard just war criteria, we analyze conditional threats of harm under Thomas Schelling's twofold distinction of compellence and deterrence. We aim to show how threats of armed attack, while subject to many of the same evaluative principles as the corresponding use of force, nevertheless have distinctive characteristics of their own. These are outlined under the headings of just cause, ad bellum proportionality, legitimate authority, and right intention. The overall aim is to explain how threats in the international sphere represent a special category that warrants a just war analysis.