During World War II, the United States and the Soviet Union fought together as allies against the Axis powers. However, the relationship between the two nations was a tense one. Americans had long been wary of Soviet communism and concerned about Russian leader Joseph Stalin’s tyrannical rule of his own country. For their part, the Soviets resented the Americans’ decades-long refusal to treat the USSR as a legitimate part of the international community as well as their delayed entry into World War II, which resulted in the deaths of tens of millions of Russians, Postwar Soviet expansionism in Eastern Europe fueled many Americans’ fears of a Russian plan to control the world. Meanwhile, the USSR came to resent what they perceived as American officials’ bellicose rhetoric, arms buildup and interventionist approach to international relations. In such a hostile atmosphere, no single party was entirely to blame for the Cold War; in fact, some historians believe it was inevitable.