No agreement could be reached with the Soviets on continued control of Germany. When the Allies decided to introduce a new currency into West Germany to counter inflation, the Soviets opposed the move. As a response, and as a means of stopping the reunification of Western Germany, the Soviets imposed a blockade on Berlin on June 18th 1948 , which had been and remained under four-power control.
The American Commander in Germany, General Clay, stated that if the Soviets managed to push the U.S. out of Berlin, the next step could be the expulsion of the U.S. from Germany and then from Europe altogether. He suggested that the U.S. break the blockade by force. President Truman decided on an airlift. The airlift was very successful, and the Soviets lifted the blockade eleven months after it was imposed.