When the United States dropped their atomic bombs on Hiroshima and Nagasaki (bombs named Fat Man and Little Boy respectively) to end the Second World War, they displayed to the world the destructive power of nuclear weapons. The United States also used this event as a sort of intimidation tactic; since the United States was the only country with this technology, they had a monopoly on nuclear weapons. Both of these points were put into play in the Berlin Airlift, which made Josef Stalin kind of jealous, but only until 1949; the Rosenbergs had passed information about the atomic bombs in the United States to the Soviet Union, leading the Soviet Union to test its first atomic bomb, RDS-1, in 1949.