Nations only get away with genocide because they have the technological prowess to do so, and that includes - but is not limited to - the ability to threaten ones enemies with nuclear annihilation.

Other means of technological prowess that can be used to get away with genocide include the mass control of information, the ability to pretend to be ones enemies, and the control of the education/stupidity of ones own citizen-subjects - who are, after all, the only truly peaceful force on Earth that can ever do anything effective about state oppression ..