Wars are fought not only by the aggressors. And the aggressor can be acting to prevent amoral behavior (attacking a state which is engaging in slavery/genocide

Wars are fought not only by the aggressors. And the aggressor can be acting to prevent amoral behavior (attacking a state which is engaging in slavery/genocide of its people, but one might argue that is an act of war in the moral sense). If one accepts that acting in a war in such a capacity is the more moral choice than inaction, then it makes sense to talk about the ethics of war, such as: when is lethal force against enemy combatants acceptable, what weapons of war have justifiable risks?