Photograph showing a West Berlin policeman (on left) talking to a Soviet Sector policeman over an East-West frontier barrier, in Berlin, 1949. This was one of a number of new barriers set up by the Soviet forces in an attempt to strengthen their blockade of West Berlin. Between April 1948 and May 1949 Stalin, leader of the USSR, imposed a land blockade on supplies from Western Europe to West Berlin. In response the British and American governments organised an enormous airlift to supply food and other essentials to the 2.5 million inhabitants of West Berlin. After a year Stalin conceded defeat and lifted the land blockade.