In 2005, US Marines killed 24 unarmed Iraqi civilians in the town of Haditha. How should we assess the perpetrators of this and other war crimes? Is it unfair to blame the Marines because they were subject to situational pressures such as combat stress? Or should they be held responsible for their actions, since they intentionally chose to kill civilians? In this text, we take up these questions and propose a provocative theory of the causes of war crimes and the responsibility of perpetrators.