April Blockade

On 1 April 1948, the Soviet military administration issues comprehensive controls for allied transit traffic from and out of Berlin. American and British military trains refuse to conform and are not allowed to pass. One day later, the Americans start supplying their Berlin troops by air, as permitted by the Air Traffic Agreement signed by the Soviet side in December 1945. On 11 April, the United States terminate their supply flights, as the Soviet side ceases their controls. However, the Western powers have now become aware of how vulnerable the access ways to Berlin are, and start developing emergency plans.