After the World War II, Germany was divided into British, French, American, and Soviet sectors. The city of Berlin, located entirely in the Soviet sector, was divided as well. In 1948, the Soviets, angered by unification of the British and American sectors of Germany, blockaded capitalist West Berlin in an attempt to starve the Americans into submission. The western Allies, unable to strike back militarily due to the risk of nuclear war, began a campaign of airlifting supplies to West Berlin. By May 1949, it was clear the blockade of Berlin had failed, and the U.S.S.R. reopened the roads that ran through their territory. The Berlin airlift had preserved West Berlin and laid the groundwork for the North Atlantic Treaty Organization (NATO).