"NATO was constructed on the - with the reason, whether one believes it or not, that it was going to defend Western Europe from Russian assault. Once the Berlin Wall fell and the Soviet Union was beginning to collapse, that reason was gone. So, first question: why does NATO exist?" - Noam Chomsky
NATO's purpose was never the ones that they proclaim openly. NATO is an American pet project, where the US treat their allies just a bit better than slaves. And this is why powerful countries such as Turkey are increasingly turning rebellious (by ordering Russian air defense systems). Ever since the collapse and disintegration of the USSR in 1992, I don't think that there have been a single positive contribution from the NATO. All they have done is to bomb third world nations such Serbia, Libya and Iraq to rubble.