By Meirion Jones
Before the Big Five official nuclear powers get too smug about North Korea, everyone's had a fizzle - when a nuclear weapon only partially explodes.
The first ever fizzle was in the USA. America's 18th bomb test went wrong not once but twice. Buster Able failed to go off at all - presumably there was a serious "do we approach the lighted touch paper?" moment before they went back to look at what had gone wrong.
Is North Korea the latest in a long line of fizzles?
Three days later on 22 October 1951 they tried again and this time the high explosive went off but the plutonium produced a yield of - errrr... nothing.
Three years later the Soviets had to deal with their first fizzle. Fortunately it was test number 15 - if it had been the first test Stalin's henchman Beria would have sent the nuclear scientists to the gulags - at best.
Both the Americans and the Russians had already had a string of successes and so they either became too complacent or were trying too risky designs.
Britain's first effort at a Hydrogen Bomb was a damp squib
Britain's first effort at a Hydrogen Bomb was also a damp squib. The force of Grapple 1 on 15 May 1957 was a quarter of the size it was expected to be. Britain claimed it had built a super bomb but the Russians and Americans just sniggered.
A Chinese H-Bomb test in 1976 was another partial failure.
India and Pakistan's tests in May 1998 were also not what they appeared. Most outside observers came to the conclusion that either both sides had exaggerated the number of nuclear tests they carried out or that some of the devices had failed.
After the collapse of the Soviet Union the Russians had to launch a fantastically expensive operation to recover a dud bomb from under Kazakhstan when it ceased to be part of Moscow's territory.
The test in North Korea has sparked a wave of angry protests
The opposite of a fizzle can be just as dangerous. America's nuttiest weapon was the Davy Crockett - a small nuclear bomb fired from a glorified grenade launcher with a range of a mile or two. In early tests the warhead over-performed and would have evaporated any Americans with a grenade launcher.
Bikini Atoll in March 1954 was the scene of the biggest overshoot when a US five megaton blast turned out to be 15 megatons - 1,000 times as big as Hiroshima. Many Pacific islanders for miles around were covered in radioactive fallout as were the crew of a Japanese fishing vessel which was 80 miles away - the Lucky Dragon - one of whom died shortly after from radiation poisoning.
As for the French on 25 April 1961, their fourth atom bomb test - delightfully-named Gerboise Verte - Green gerbil - was also a fizzle but that was because it was deliberately set off early in case coup plotters seized the live bomb and held France to ransom. These things happen.