Was 1945 a turning point in the frame of international relations? This essay deals with the main features of the post-world war era, beginning from the victory of the "strange alliance". Despite some ambiguity, it was the victory both of antifascism and of an open international order concept. The shifting of international system towards bipolarism and the cold war was obviously important, but did not modify the situation deeply. The new enclosed imperial soviet sphere of influence had no power to condition the development of the dynamic new economically open international order led by the United States, which was the fruit of a great compromise between the European states and the America superpower. This system was stable because the cold war made it easier to shake off old nationalisms, and both superpowers decided to compete by non-military means. The essay suggests that the mood of the cold war was not such as to expunge the antifascist bases of the new international order.