After World War II, Oppenheimer resigned from Los Alamos and returned to academia, but he was no longer satisfied by life in the ivory tower. His work at Los Alamos had left him with a feeling of responsibility for the state of the nation, as well as a taste for the power and prestige that came with being a public figure. So Oppenheimer became the public face of American physics, speaking out on how he felt the United States should handle its powerful new atomic weapon. Oppenheimer was both proud of and frightened by the atomic bomb that he and his fellow scientists created. It was a masterful technical achievement, but it was also a powerful killing machine. Having released nuclear power upon the world, Oppenheimer felt responsible for ensuring that power was used for good–or, at least, to ensure it would not be used for evil. He continually, and always unsuccessfully, pressed for some form of international controls on nuclear power, believing that only communication and cooperation between the world powers could keep the country safe in a nuclear age. But Oppenheimer also felt a responsibility to continue providing for the national security of his country and thus did not fight against the development of a nuclear program. He only tried to keep that program from spiraling out of control. Oppenheimer remained in Washington as a voice of nuclear moderation until he was forced out by those who believed his opinions were dangerously wrong.

Those on the side of the development of the hydrogen bomb argued that the powerful bomb was the only appropriate answer to the Soviet Union's explosion of an atomic bomb. If that explosion had put the United States and the Soviet Union on an equal level, they argued, the creation of a Super bomb would once again give the United States the upper hand. If the United States did not proceed with a hydrogen bomb, they continued, it was inevitable that the Soviet Union would, since the "Evil Empire" would not be stopped by the same more qualms that might make the United States hesitate. On the other side of the debate, the opponents of the hydrogen bomb insisted that it was not necessary to preserve national security. If the Soviet Union did build a hydrogen bomb, the United States would have enough power in its store of atomic bombs to match the Soviet threat. Further, these opponents insisted that as long as a hydrogen bomb was not a necessity, it should not be built. Such a weapon could never be part of a targeted military strategy, since it was so powerful that its only possible use was genocide, the annihilation of an entire people. The opponents of the hydrogen bomb argued that the world would be a better place were such a weapon never created, and the United States would be a better country for having refrained from creating it.

The Board eventually decided that Oppenheimer was a loyal citizen of the United States, and they pointed to his distinguished record of service to the country and affirmed that they did not believe he was, or had ever been, a spy for the Soviet Union. Unfortunately for Oppenheimer, they nonetheless voted to remove his security clearance. The Board cited his reluctance to tell the truth about incidents in his past–notably the Chevalier incident, in which Oppenheimer had been solicited to spy for the Soviet Union and then failed to report the incident–as one of the major causes for their decision. Oppenheimer may not be lying, they decided, but nor is he telling the complete truth. The Board also criticized Oppenheimer's behavior during the debate over the creation of a hydrogen bomb, suggesting that his stance on the Super may not have been in the best interest of national security. Essentially, the Board criticized Oppenheimer's judgment and personality, asserting that while he had done nothing wrong intentionally, he had often made decisions that were not in the nation's best interest and had shown a consistent refusal to follow the rules.