The Mass Atrocity Response Operations (MARO) Project seeks to enable the United States and the international community to stop genocide and mass atrocity as part of a broader integrated strategy by explaining key relevant military concepts and planning considerations. The MARO Project is based on the insight that the failure to act in the face of mass killings of civilians is not simply a function of political will or legal authority; the failure also reflects a lack of thinking about how military forces might respond. States and regional and international organizations must better understand and prepare for the unique operational and moral challenges that military forces would face in a MARO. Such an effort offers several benefits, including the creation of a wider range of potentially effective military responses. Advance planning with possible partners would greatly facilitate coalition operations. Developing more effective intervention options may help strengthen deterrence of would-be perpetrators.