Controversies involving Alger Hiss and Julius and Ethel Rosenberg reflected the post-World War II concern over (4) spying by communists in the United States. Alger Hiss had first been said to have been a Communist, but not a Soviet spy, however it later emerged he was a spy and he was tried several times for this. Julius Rosenberg was tried and executed for having passed information about the nuclear bomb to the Soviet Union, which he did, however his wife did not do anything and she was tried and executed as well.