Monday’s explosion of a nuclear device by North Korea, if true, makes the Communist-ruled state the latest member of the elite club of nuclear powers. Still unclear, however, is the reach of a North Korean nuclear threat. While details of the country's nuclear capabilities are scant, the arsenal is believed to be small.
HOW MANY BOMBS:
• A successful test would indicate North Korea had at least one assembled nuclear device.
• It is unclear how many more might be ready to go. Estimates of the amount of radioactive material the North possesses varies widely, enough for possibly between four and 13 weapons, and are unverifiable.
• The count compares with a United States arsenal of more than 5,000 strategic warheads, more than 1,000 operational tactical weapons — meant for the battlefield and less powerful than the strategic arms — and approximately 3,000 reserve strategic and tactical warheads.
• Measurements of Monday's test signals an explosion equivalent to about 550 tonnes of TNT, a state-run South Korean geological institute said.
• By contrast, the atomic bomb dropped on Hiroshima of Japan on August 6, 1945, had the destructive power of about 15,000 tonnes (33 million pounds) of TNT. Another bomb dropped in Nagasaki was equivalent to about 21,000 tons (46.2 million pounds) of TNT.
• A top concern is the possibility of North Korea mounting bombs atop missiles aimed at Seoul, Tokyo or even parts of the United States.
• The North's ability to accurately deliver a warhead toward its neighbours is in doubt. The communist nation shocked the world in 1998 by firing a long-range ballistic missile over Japan into the Pacific Ocean.
• In July, North Korea test-launched seven missiles, but a long-range rocket believed capable of reaching American shores exploded shortly after liftoff.
However, the country isn't believed to have a nuclear weapons design that would be small and light enough to be mounted atop a missile.
• North Korea is believed to have been accumulating plutonium for a bomb since the mid-1980s. It froze the programme in 1994 as part of an agreement with the US. Since the breakdown of that agreement in late 2002, North Korea is believed to have ramped up production.
• Some experts estimate that at least 80 percent of the country's stockpile of 20 to 53 kg (44 to 116 pounds) of refined plutonium was processed since the end of the freeze in 2002. Without another agreement to limit the country's plutonium production, North Korea is forecast to boost its stockpile to 53 to 73 kg (116 to 160 pounds) by 2008.
• Of that amount, an estimated 40 to 68 kg (88 to 150 pounds) would be refined and usable in nuclear weapons, enough to build between eight and 17 bombs.
(Source: Institute for Science and International Security.)