Penalizing Atrocities

The Syrian Civil War that began in 2011 killed more than 400,000 civilians. Could a limited intervention motivated by humanitarian concerns have reduced the death toll at an acceptable cost to the intervenors? I distinguish between two approaches to intervention: penalizing atrocities, by raising the cost and lowering the benefit of killing civilians; and fostering a balance of power, to convince the two sides that they cannot win on the battlefield and so must negotiate an end to the war. I show, using a game-theoretic model, that fostering a balance of power causes the government to commit more atrocities and prolongs the war. Penalizing atrocities, while it increases the likelihood of war, can reduce the expected level of atrocities. The model helps account for the failure of US efforts to promote negotiations by aiding Syrian rebels, and the success of efforts to deter Syrian chemical weapons use through threats and limited strikes.