The beginning of the Cold War refers to the emergence of political, ideological, economic and military rivalry between the United States and the Soviet Union after the end of the Second World War. Although the two powers had cooperated against Nazi Germany, their fundamentally different political and economic systems and competing security interests soon created deep tensions. The Cold War gradually developed between 1945 and 1949 and divided Europe into two opposing blocs. The roots of the Cold War can be traced to the ideological conflict between capitalism and communism. The United States supported liberal democracy, private property and a capitalist economy, while the Soviet Union promoted a communist political and economic system based on state ownership and one-party rule. Mutual suspicion had existed since the Russian Revolution of 1917, but the alliance during the Second World War temporarily suppressed these differences. The defeat of Germany in 1945 created a power vacuum in Europe. Soviet forces occupied much of Eastern Europe and established governments sympathetic to Moscow in countries such as Poland, Hungary, Romania, Bulgaria and Czechoslovakia. The Western powers viewed the expansion of