The Oppenheimer security hearing, conducted by the United States Atomic Energy Commission (AEC) over four weeks in 1954, explored the background, actions, and associations of J. Robert Oppenheimer, the American scientist who directed the Los Alamos Laboratory during World War II as part of the Manhattan Project to develop the atomic bomb. The hearing resulted in Oppenheimers Q clearance being revoked. This marked the end of his formal relationship with the government of the United States, and generated considerable controversy regarding whether the treatment of Oppenheimer was fair, or whether it was an expression of anti-communist McCarthyism.