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<unk> <unk> <unk> <unk> <unk> <unk> <unk> <unk> <unk> <unk> <unk> <unk> <unk> <unk> <unk> <unk> <unk> <unk> <unk> Because Berlin was located within the Soviet-occupied zone of Germany, the only available methods of supplying the city were three limited air corridors.<unk> Because Berlin was located within the Soviet-occupied zone of Germany, the only available methods of supplying the city were three limited air corridors. A massive air supply campaign was initiated by the United States, Britain, France, and other countries, the success of which caused the Soviets to lift their blockade in May 1949.