Answer:
West Berlin was occupied by allied troups of the United States, the United Kingdom and France in 1945. East Berlin was occupied by troups of the Soviet Union. West Germany regarded West Berlin as a part of the Federal Republic of Germany for Greater Berlin was mentioned in the Basic Law, the West German constitution. But the Allied (U.S., UK and France) claimed sovereignity over all of Berlin. The German Democrat Republic and the Soviet Union regarded West Berlin as an independent state and East Berlin as a part of East Germany. West Berlin regarded itself as a part of West Germany. So the status of West Berlin remained uncertain until 1990. Nowadays most Germans agree that life in West Berlin was better than in East Berlin.