International humanitarian law (IHL), now synonymous for many withjus inbello, is the branch of international law that governs the conduct of war. Eventhough the main instruments of IHL have been universally ratified, however,and IHL is perhaps the most effective means so far developed to limit theeffects of war, it is notoriously difficult to implement and enforce (Sassòli2007, 46–47; Bartles-Smith 2022, 1726). The extreme conditions of armedconflict are inherently anarchic, and diminish, furthermore, the resolve andability of belligerents to regulate themselves (Sassòli 2007; Pfanner 2009,280). While the law is a necessary condition for regulating armed conflict, itis not therefore always sufficient, and extra-legal means must be sought toimprove compliance with it (Sassòli 2007; 52, 73; Bartles-Smith 2022, 1727).In recent years organisations like the International Committee of the RedCross (ICRC) have opened up debate on correspondences between IHL andreligious traditions to promote compliance with common humanitariannorms (ICRC 2021a; Bartles-Smith et al. 2020). Given that serious violationsof IHL continue to occur in parts of the Buddhist world, and Buddhists areincluded in the armed forces of many other nations, the ICRC launcheda project on Buddhism and IHL in 2017 (ICRC 2019a). Surprisingly littleattention had hitherto been paid to Buddhism’s potential to inform theconduct of contemporary war (Bartles-Smith et al. 2020, 370–372). AlthoughBuddhists have beenfighting wars for two and a half millennia, Buddhismand war are commonly regarded as incompatible, and Buddhist resources torestrain war are often therefore unexplored (Harris 2003, 93–94).This article compares Buddhism with IHL and the Western just war tradi-tion by which it has been informed, and explores whether Buddhism cansupport IHL to humanise the conduct of war. It argues that Buddhism is inbroad alignment with IHL, and that the fundamental principles of Buddhistethics mean that it is in the interest of belligerents to minimise the harm theyinflict on others, and the karmic consequences to themselves, very much inline with IHL principles (Harvey 2021, in this volume). Many Buddhist teach-ings therefore correspond with IHL rules and contain stories and anecdotes ofexemplary restraint (Bartles-Smith et al. 2020).Comparing Buddhism with IHL is not, however, to compare like with like,and means examining the relative strengths and weaknesses of two verydifferent normative systems. Indeed, these differences are as revealing astheir similarities, and can throw fresh light on how the conduct of war mightbe improved. Although the content and jurisdiction of IHL are intended to beuniversal, it is nevertheless Western in design, and engagement withBuddhism can make it more accessible to many Asian constituencies inparticular (Caserta 2021; Kinsella and Mantilla 2020; Bartles-Smith 2022, 1731). Whereas IHL is a secular international legal regime that lays down clearlycodified rules for belligerents to follow, Buddhism is at once a religion,philosophy and practical path to human development, encompassing diversetraditions that interpret it in different ways (Gethin 1998, 1; Jerryson 2010, 5).Many scholars prefer for this reason to speak of Buddhisms in the plural(Gethin 1998, 1). The main schools nevertheless tend to converge upon thecentral tenets of Buddhist teaching, and it is primarily this ethical and psy-chological core from which the article will draw (Keown 2005, 3).