11. The hydrogen bomb was developed by the United States in the early 1950s
After the Soviet Union demonstrated to the world that they possessed an atomic bomb the United States redoubled its efforts to develop ever more powerful weapons to counter the new Soviet threat. Both new means of delivering the weapon and more powerful weapons themselves were designed, engineered, and those with promise deployed. In 1952 the United States detonated a new type of bomb, in which a primary stage fission bomb releases radiation which bombards a secondary fusion stage, creating a fusion reaction. Later designs added a third stage. The hydrogen bomb, as it came to be called for its use of hydrogen isotopes in its fusion stage, was a far more powerful device than the plutonium implosion bomb, and allowed for smaller weapons which delivered a far greater yield.
The five major nuclear powers all developed hydrogen bombs of their own throughout the ensuing decade (the five powers were the United States, the Soviet Union, the United Kingdom, France, and the People’s Republic of China). They have since been joined by India, Pakistan, South Africa, Israel, and following the dissolution of the Soviet Union several former Soviet Socialist Republics. North Korea has recently developed nuclear weapons, and several other states are suspected of either possessing or being in the process of acquiring them. Delivery devices are another matter. Throughout the 1950s the United States developed a means of delivering strategic nuclear weapons to their targets relying on three major legs of what came to be known as the nuclear triad; land-based intercontinental ballistic missiles, submarine-launched intercontinental ballistic missiles, and land-based strategic bombers.