On 23 June 1948, the Soviet Union blockaded traffic into West Berlin to place pressure on Western Powers. This event signalled the beginning of the Cold War. On 24 June, the Soviet Union announced that the Allies had no right to be in Berlin. As a response to the blockade, the U.S. and Great Britain organized an airlift to provide the people with water and food. The airlift lasted for the next 11 months. It cost a total of $224 million and the Allies provided the West Germans with over 2,000,000 tons of supplies. The Soviet blockade was halted on 12 May 1949. And the airlift ended on 30 September.
Richert, Lucas Paul. "Berlin Blockade and Airlift". The Literary Encyclopedia. First published 01 November 2008
[http://www.litencyc.com/php/stopics.php?rec=true&UID=5628, accessed 24 May 2013.]