All four Allies shared administrative responsibilities for Berlin. However, in 1948, when the Western Allies extended the currency reform in the Western zones of Germany to the three western sectors of Berlin, the Soviet Union imposed a blockade on the access routes to and from West Berlin, which lay entirely inside Soviet-controlled territory. The Berlin airlift, conducted by the three western Allies, overcame this blockade by supplying food and other supplies to the city from June 1948 to May 1949. In 1949, the Federal Republic of Germany was founded in West Germany and eventually included all of the American, British and French zones, excluding those three countries' zones in Berlin, while the Marxist-Leninist German Democratic Republic was proclaimed in East Germany. West Berlin officially remained an occupied city, but it politically was aligned with the Federal Republic of Germany despite West Berlin's geographic isolation. Airline service to West Berlin was granted only to American, British and French airlines.