Fulfilling agreements reached at various wartime conferences, the Soviet Union promises to hand power over to British and U.S. forces in sectors of Allied-controlled Berlin. Although the division of Berlin (and of Germany as a whole) into zones of occupation was seen as a temporary postwar expedient, the dividing lines quickly became permanent. The divided city of Berlin became a symbol for Cold War tensions. During a number of wartime conferences, the United States, Great Britain, and the Soviet Union agreed that following the defeat of Germany, that nation would be divided into three zones of occupation. Berlin, the capital city of Germany, would likewise be divided. When the war in Europe ended in May 1945, however, Soviet troops were in complete control of eastern Germany and all of Berlin. Some U.S. officials, who had come to see the Soviet Union as an emerging threat to the postwar peace in Europe, believed that the Soviets would never relinquish control over any part of Berlin. However, on July 11, 1945, the Russian government announced that it would hand over all civilian and military control of West Berlin to British and American forces. This was accomplished, without incident, the following day. (The United States and Great Britain would later give up part of their zones of occupation in Germany and Berlin to make room for a French zone of occupation.) In the years to come, West Berlin became the site of some notable Cold War confrontations. During 1948 and 1949, the Soviets blocked all land travel into West Berlin, forcing the United States to establish the Berlin Airlift to feed and care for the population of the city. In 1961, the government of East Germany constructed the famous Berlin Wall, creating an actual physical barrier to separate East and West Berlin. The divided city came to symbolize the animosities and tensions of the Cold War. In 1989, with communist control of East Germany crumbling, the Berlin Wall was finally torn down. The following year, East and West Germany formally reunited.