The beginning of the Cold War can be traced to the growing political, ideological, economic and military rivalry between the United States and the Soviet Union after the end of the Second World War in 1945. Although the two powers had cooperated against Nazi Germany during the war, their fundamentally different political and economic systems created deep mutual suspicion. The United States represented liberal democracy and capitalism, while the Soviet Union promoted communist ideology and a centrally planned economy. The wartime alliance began to weaken even before the defeat of Germany. The question of the future of Eastern Europe became a major source of disagreement. The Soviet Union sought friendly and pro-Soviet governments in Eastern Europe as a security measure against possible future invasions. The United States and Britain, however, regarded Soviet expansion as a threat to political freedom and the balance of power in Europe. The establishment of communist governments in Poland, Romania, Bulgaria and other Eastern European countries increased Western fears of Soviet domination. The conferences of Yalta and Potsdam revealed these differences. At Yalta in February 1945, the Allies agreed that liberated