The Soviet Union suffered grievous losses during World War II. Much of its European territory was devastated by mechanized warfare and the horrors of occupation. Official Soviet reports at the time stated that 20 million soldiers and civilians perished in the war, but it was later revealed, during Gorbachev’s time in office in the 1980s, that a more realistic figure for Soviet losses was between 27 million and 28 million. At this astronomic price, the Soviet Union subdued its bellicose neighbors, expanded its frontiers, and moved its troops into Germany, Eastern Europe, and formerly Japanese-held parts of East Asia. Bargaining over postwar arrangements afforded it recognition as one of the great powers of the world. Stalin participated with the American and British leaders at the Tehr?n Conference in 1943, the Yalta Conference in February 1945, and the Potsdam Conference later in 1945 to decide the overall military and political strategy of the war and a common postwar European policy. The Soviets also played a leading role in the conferences leading to the establishment of the United Nations (UN) in 1945.