The USSR also played a leading role in the preliminary international conferences leading to the establishment of the United Nations in 1945.

Instead of making a treaty immediately with defeated and disorganized Germany, the victorious powers temporarily designated four occupation zones. The eastern zone was assigned to the USSR. Berlin, surrounded by the Soviet zone, was divided into four sectors, and its eastern zone was also assigned to the USSR. The occupied zones were to be administered as parts of one country, with free trade among them. German territory east of a line formed by the Oder and Neisse rivers was assigned to Polish occupancy pending a final peace settlement. The northern part of East Prussia was ceded to the USSR. The Soviet Union, however, set up its own type of government in the areas assigned to it, and by 1947 the so-called Iron Curtain had been drawn to divide Eastern and parts of Central Europe from Western Europe. The USSR, having suffered enormous losses, exacted huge reparations in the form of dismantled industrial plants and the output of current production. It also benefited from the forced labour of millions of German prisoners of war.