This book explores the overarching phenomenon of how force short of war is being used in modern conflict, and how it impacts just war theory. It shows that we need to bring the rules of war into alignment with increasingly digital means of conducting kinetic warfare through the force short of war paradigm. The use of force short of war is now commonplace, in large part owing to casualty averseness and the explosion of emerging technologies, most notably drones, autonomous robotics and cyber. It often involves the selective or limited use of military force to achieve political objectives and assumes many forms. These include targeted killing, assassination, the establishment of no-fly zones, special-forces raids, limited duration bombing campaigns or missile strikes, and 'low intensity' counterterrorism and counterinsurgency operations.