The end of the Cold War and the events that marked the previous decade up to the allied intervention in Kosovo pointed towards the likelihood of a progressive US withdrawal from alliances in general, and NATO in particular. The emergence of European Defense, together with structural evolutions in US society and the political classes, would appear to emphasize this phenomenon.

Against the trend, this paper intends to show that the continuation of a US presence in Europe and NATO's survival may be explained through the essential functions that the Organization fulfils. These functions are vital, both politically and militarily, for the world leadership of the US.

For this reason, the different reforms undertaken in the Alliance arose, on the US side, within the context of a well-thought out plan with twin objectives: the preservation of the traditional advantages of the Atlantic Alliance; and the adaptation of the Organization to an internal and external context that has profoundly changed over a 10 year period. In the longer term, however, the future of NATO will be assured by mutual efforts between Americans and Europeans, in terms of increased political flexibility and enhanced military interoperability.