In 1948 a United States emphasized a need to reconstruct a German economy after World War II. The Soviets conflict to a introduction of a Deutsche Mark by tightening checkpoints to a French, British and American sectors of Berlin, eventually heading to a belligerent besiege of a city. To keep a city from starvation, a Western allies start a Berlin Airlift, ferrying in reserve by plane. The besiege finished on May 12, 1949.