 Much recent work has used either traditionalist or revisionist just war theory to consider new developments in the practice of warfare, especially the use of drones, and the possible development of autonomous weapons systems. Others have focused on the ethics of non-state conflicts, and asymmetric wars. Very few contemporary wars fit the nation-state model of the mid-twentieth century, and conflicts involving non-state actors raise interesting questions for legitimate authority and the principle of Discrimination in particular (Parry 2016). A third development, provoked by the terrible failure to plan ahead in Iraq and Afghanistan, is the wave of reflection on the aftermath of war. This topic, jus post bellum, is addressed separately.