The 'Nuclear Club' expands
Although the race to build the "super" had been achieved by both the United States and the Soviet Union, the other nuclear powers also pursued development of their own hydrogen bombs. In 1954, Prime Minister Churchill decided that Britain should begin its own hydrogen bomb program. On November 8, 1957 over Christmas Island (Kiribati), the British exploded a 1.8 megaton hydrogen bomb.
On June 14, 1967, China became the next nation to detonate a hydrogen bomb. They detonated their first thermonuclear bomb just 32 months after their first atomic bomb. The test had a yield of 3.3 megatons.
The final nation to successful explode an thermonuclear device was France. Their device was tested over Fangataufa Atoll in the Pacific on August 24, 1968. It produced a yield of 2.6 megaton and severely contaminated the atoll.
Although both India and Pakistan have claimed to have tested some form of thermonuclear device or boosted fission device during their nuclear tests in 1998, these claims have not been verified and are in dispute. Although never publicly declaring that they have nuclear devices, Israel's arsenal is believed to be fission based.
Weapons designers continued working on refining the early crude thermonuclear devices. They developed devices that produced high levels of radioactive fallout (salted bombs), or enhanced radiation weapons (neutron bombs). However, their principle focus was on miniaturization. The first deliverable hydrogen bombs typically weighed nearly 40,000 pounds. Now most thermonuclear weapons weigh under 800 pounds, allowing them to be placed on a variety of delivery devices from intercontinental ballistic missiles to artillery shells.
The World's Current Nuclear State
Currently, the majority of the world's 26,000+ nuclear weapons are comprised of thermonuclear based bombs. Beyond the existing stockpiles, there are other nations that appear to actively pursuing some form of a nuclear weapons program. In 2006, North Korea appeared to have detonated some form of limited nuclear device. However, it seems that they are agreeing to dismantle their weapons program. The true intent of Iran's nuclear program is also a mystery. Many observers feel that it is a clandestine effort to build nuclear weapons, however Iran claims it is only to develop the infrastructure for nuclear power.
What lies ahead in the atomic age is unknown, but the nuclear genie is out of the bottle.