The war in Ukraine is fast approaching its second anniversary since its commencement on 24 February 2022 as a blatant aggression by Russia. As we discuss in detail in this book, there are multiple international legal issues that arise and require addressing. What is more, the very international legal order is under threat, insofar as the fundamental international law obligations are not being complied with and the basic international rules are utterly ignored. This book discusses a number of international law issues arising from the war in Ukraine. It covers not only the traditional subjects of war, such as jus ad bellum, international criminal law, and the law of neutrality, but also the relatively new issues arising from the economic sanctions against Russia, including aspects of the WTO law and international investment law. This book provides the readers with opportunities to reconsider the various legal aspects of the war in Ukraine.