In the years following the end of World War II, the United States gradually found itself confronting a new enemy: the Soviet Union. At the outset of the Cold War, as the new period of international tension was called, the United States had a single, gigantic advantage, since it maintained a nuclear monopoly. As long as the United States had the bomb and the Soviets did not, there could be no question as to which country was the world's number one superpower.
Oppenheimer had originally argued that the United States should tell its Soviet allies about the bomb project during the war, partly in the hopes of avoiding a future arms race. But the government rejected this idea, choosing instead to keep the bomb program a secret and eventually relishing their nuclear superiority.
But as the physicists knew, there was no big secret to nuclear power, only some fundamental physical principles and a large number of technical problems to figure out. This meant that it was only a matter of time before the Soviets were able to construct their own atomic bomb. Estimates of how long this would take varied; some argued it would take the Soviets ten years, others suggested it might only be four or five. It seems, however, that no one was listening to their warnings, for when the Soviet Union set off a nuclear explosion in September of 1949, the United States was taken by complete surprise.
The country was shocked, and the always-cautious government assumed that this must mean there had been Soviet spies within Los Alamos. Oppenheimer, once again, became a prime target of suspicion. But as investigators tried to determine exactly how the Soviet bomb program had gotten its information, government officials were scrambling to decide on an appropriate American response to the new Soviet nuclear threat.
One suggestion set off a year's worth of top-secret debate and controversy among the highest levels of the government, military, and scientific community. It was the suggestion that the only way to appropriate way to react to the Soviets getting the bomb was to one-up them by developing what scientists liked to call "the Super," or, more technically, a hydrogen bomb.
After the war, physicist Edward Teller had stayed at Los Alamos, working with a team on a new type of bomb, the hydrogen bomb, which would generate energy by fusing together hydrogen atoms. Such a bomb would be hundreds of times more powerful than the ones dropped on Japan. While a hydrogen bomb was theoretically possible, there was still some question as to whether the physicists could actually build one.