This book explores the ethical implications of war in the contemporary world. The author, a leading theorist of warfare, explains why it is of crucial importance that Western countries should continue to apply traditional ethical rules and practices in war, even when engaging with international terrorist groups. The book uses the work of the late American philosopher Richard Rorty to explain the need to make ethical rules central to the conduct of military operations. Arguing that the question of ethics was re-opened by the ‘War on Terror’, the book then examines America’s post-9/11 redefinition of its own prevailing discourse of war. It ends with a discussion of other key challenges to the ethics of war, such as the rise of private security companies and the use of robots in war. In exploring these issues, this book seeks to place ethics at the centre of debates about the conduct of future warfare.