Racism, especially antisemitism, was a central feature of the Nazi regime. In Germany, but predominantly in the German-occupied areas, the systematic genocide program known as the Holocaust killed 17 million, including Jews, German dissidents, disabled people, Poles, Romanies, Soviets (Russian and non-Russian), and others. In 1942, the German invasion of the Soviet Union faltered, and after the United States entered the war, German cities became targets for massive Allied bombing raids. It has been estimated that in all about 353,000 German civilians were killed and 9 million left homeless during the Allied bombing raids. Following the Allied invasion of Normandy (June 1944), the German Army was pushed back on all fronts until the final collapse in May 1945. Under occupation by the Allies, German territories were split up, Austria was again made a separate country, denazification took place, and the Cold War resulted in the division of the country into democratic West Germany and communist East Germany, reduced in territory by the establishment of the Oder-Neisse line. Millions of ethnic Germans were deported from pre-war Eastern Germany, Sudetenland, and from all over Eastern Europe, in what is described as the largest scale of ethnic cleansing in history. Germans also fled from Communist areas into West Germany, which experienced rapid economic expansion, and became the dominant economy in Western Europe. West Germany was rearmed in the 1950s under the auspices of NATO but without access to nuclear weapons. The Franco-German friendship became the basis for the political integration of Western Europe in the European Union.