"They will want to test until they get it right," said Michael Swaine, a senior associate in the China program at the Carnegie Endowment for International Peace in Washington, at an Oct. 12 seminar on the North Korean situation.
Such misfires aren't necessarily symbols of incompetence. Almost all declared nuclear powers have had them. In October 1951, a US bomb test named Buster Able failed not once, but twice. The Soviets had a misfire in 1954. In May 1957, Britain's first attempt at exploding a hydrogen bomb produced only a quarter of the expected yield.
In the case of North Korea, whatever went wrong, it probably was not due to haste. Satellite photos of the suspected test site released Oct. 13 by the Natural Resources Defense Council (NRDC) show that neither buildings nor roads changed much from late 2005 to October 2006.
"The North Koreans probably did not rush the test," wrote physicist Matthew McKinzie, an NRDC consultant, in an analysis of the photos.
Indeed, the photos show that excavation activity for the test may have been carried out in February 2005.
Instead, the misfire may indicate that the device was a somewhat sophisticated plutonium-fueled bomb, according to the NRDC.
Via atmospheric sampling, US intelligence has determined that plutonium was used in the North Korean test, according to news reports. For such a weapon to explode efficiently, the plutonium core must be "squeezed" by conventional explosives in a highly precise manner.
"It is possible that the detonators igniting the high explosive that compresses the plutonium did not fire simultaneously and thus only produced a partial yield," concludes the NRDC analysis.
Though North Korea's interest in nuclear science was well known in the West, it was not until the mid-1980s that US intelligence began to become alarmed about Pyongyang's intentions.