The article shows some parts of the process of establishing post-war system of international relations, which was based on the agreements of the Allies (the Soviet Union, the US and the UK) achieved at the Yalta and Potsdam international conferences. The ability of allies to negotiate, to seek compromises in a joint struggle against the common enemy is noted. The picture of the post-war Germany and the fate of the German population and the major war criminals is shown. It was certainly taken into account in the negotiations between the allies. Against this background, the authors address the issue of transformation of post-war security in the modern period and express the view that the problem was caused by dismantling of the bipolar confrontation, the end of which was placed by the collapse of the Soviet Union and the collapse of the socialist community. The process took place under conditions of self-identification of new actors in international relations and the attempts of the leading western powers to establish the rules of international conduct that could be profitable for them. The authors conclude that there is necessity to preserve the historical memory, which will help raise the level of political responsibility before the world community. The need to address contemporary problems of humanity, such as the prevention of the threat of nuclear war, the fight against international terrorism, the prevention of regional military conflicts demonstrate the need for cooperation of the largest nuclear powers in the world. From this point of view, it is updated study of the historical experience of the interaction of the anti-Hitler coalition in the war and post-war periods.