http://en.wikipedia.org/wiki/Berlin_Air_Safety_CenterThe Soviet Union is infringing upon the Berlin Air Safety Center's ability to operate three 20-mile wide air corridors that the United Kingdom, France, the United States, and the Soviet Union have
no restriction rights towards.
"The BASC coordinated air traffic in and out of Berlin and was responsible for air safety in the three corridors established in 1946 as well as in the Berlin Control Zone, the airspace within a 20-mile radius of a pillar in the cellar of the Allied Control Authority Building. Each of the three corridors were 20 miles wide and linked Berlin with the Western Zones of Occupation of Germany (later West Germany).
The three corridors were open without restriction only to the Four Power nations, United Kingdom, United States, France and USSR - other nations wishing to use the corridors had first to request and obtain permission from BASC."