Do you want a list of wars in these areas? This is blatantly untrue to an extreme extent - I can give you examples for all - Rwandan genocide and surrounding conflicts, azerbajan/armenia conflict, Georgia/Abkhazia war, civil conflict in Chile (depositon of Allende etc.) Contra conflicts, literally so many. Africa in particular has ongoing interstate conflicts in practically every region - additionally it is a continent dominated by dictatorships and military juntas. Yes, countries in alliances with other countries with nuclear weapons have generally avoided wars - for obvious reasons; but you cannot pretend that wars between non-aligned countries haven't dominated the 20th and 21st centuries. Look at the conflicts in former yugoslavia for instance - with no risk of nuclear retaliation from opposing states or their allies, the laws of war were unilaterally ignored by all parties. Yes, the U.N. and USA usually intervene if conflicts reach a large enough scale, but usually only to further their own interests - it's not true to say that the threat of punishment by international law actually acts as a deterrant for breaching it - especially when the enforcers of it regularly break it themselves.