neither syria or rwanda was a war, they were atrocities. in rwanda you have the government institutionalizing racial purges against a minority, giving people the freedom to go out at night and chop children up with machetes. in syria you have the government institutionalizing rape and torture against peaceful protesters and then authorizing airstrikes on civilian cities
sometimes intervention is necessary. if you see a woman being raped in an alley, you don't just say 'man i should mind my own business / it doesn't affect me therefore i shouldn't care'