 This had come about as a result of an agreement among the United States, the United Kingdom, France, and the Soviet Union at the end of World War II which prohibited Germany from having its own airlines and restricted the provision of commercial air services from and to Berlin to air transport providers headquartered in these four countries.Rising Cold War tensions between the Soviet Union and the three Western powers resulted in unilateral Soviet withdrawal from the quadripartite Allied Control Commission in 1948, culminating in the division of Germany the following year.These events, together with Soviet insistence on a very narrow interpretation of the post-war agreement on the Western powers' access rights to Berlin, meant that until the end of the Cold War air transport in West Berlin continued to be confined to the carriers of the remaining Allied Control Commission powers, with aircraft required to fly across hostile East German territory through three wide air corridors at a maximum altitude of .