One such atrocity took place in the early '90s. For four years, the world stood silent while Bosnian Serbs methodically murdered over 200,000 Muslim civilians. Throughout this ethnic cleansing operation, Serbs forced Muslim men and boys into makeshift concentration camps. Women and girls were repeatedly raped. Serbs rounded up 8,000 men and boys and brutally executed them. In retaliation, after years of inaction, U.S.-led NATO forces bombed Serbian bases, putting an end to the carnage.