In 1947, Oppenheimer was appointed director of the Institute for Advanced Study in Princeton, New Jersey, and chairman of the General Advisory Committee of the new United States Atomic Energy Commission (AEC). He lobbied for international control of nuclear power to avert nuclear proliferation and a nuclear arms race with the Soviet Union, and opposed the development of the hydrogen bomb, partly on ethical grounds. During the second Red Scare, these stances, together with his past associations with the Communist Party USA, led to an AEC security hearing in 1954 and the revocation of his security clearance. He continued to lecture, write, and work in physics, and in 1963 was given the Enrico Fermi Award as a gesture of political rehabilitation. In 2022, the U.S. federal government vacated the 1954 revocation of his security clearance.