Why did President Harry S. Truman approve development of the hydrogen bomb?

President Harry S. Truman authorized the development of the hydrogen bomb in 1950 primarily to maintain a technological and military lead over the Soviet Union during the Cold War.51

Following the Soviet Union's first successful atomic bomb test in 1949, which ended the American nuclear monopoly, the Truman administration concluded that the United States needed to pursue thermonuclear weapons to ensure its strategic superiority. Truman disregarded opposition from influential scientists, such as J. Robert Oppenheimer, who warned of the extreme dangers to humanity, on the grounds that the Soviet Union would not be constrained by similar moral inhibitions.2314

Ultimately, the decision was driven by the belief that the United States had to remain ahead in the arms race to deter potential aggression. The administration also viewed the development of these weapons as a way to extend the time needed to build up conventional forces to match those of the Soviet Union and its satellites.512