No they didn’t and the pentagon knows that for sure.
http://www.globalsecurity.org/wmd/world/dprk/nuke.htm
As of February 2005 Defense Intelligence Agency analysts were reported to believe that North Korea may already have produced as many as 12 to 15 nuclear weapons. This would imply that by the end of 2004 North Korea had produced somewhere between four and eight uranium bombs [on top of the seven or eight plutonium bombs already on hand]. The DIA’s estimate was at the high end of an intelligence community-wide assessment of North Korea’s nuclear arsenal completed in early 2005. The CIA lowballed the estimate at two to three bombs, which would suggest an assessment that the DPRK either had not reprocessed a significant amount of plutonium from the 8,000 spent fuel rods removed from storage in early 2003,
http://www.cfr.org/content/publications/attachments/North_Korea.pdf (Jan 2006)
... ‘this much material would give NK the ability to produce 6-8 nuclear weapons’....
(it includes a 1990 Soviet KGB report to the Soviet Central Committee on North Korea’s nuclear program...The KGB report asserted that “”According to available date, development of the first nuclear device has been completed at the DPRK nuclear research center in Yongbyon”
The North Koreans claimed their test was so successful it released no radiation. With no witnesses and no radiation leakage, do we just have to take their word for that the "test" wasn't a fake?
No. Since the gases produced by a chemical explosion are much cooler than those of a nuclear one, the difference will show up in the "sharpness" of the seismic pulse reading - how sharp and steep the leading edge of the reading rises. Since such sharpness is dispersed over distance, only sensors placed very close to the explosion can determine if it has the requisite sharpness to be nuclear - such as those placed by the US Navy on the floor of the Sea of Japan right off the coast of North Korea.
Those sensors' readings are classified and will remain so - yet the initial reaction of folks at the Pentagon tells me that the explosion was indeed nuclear, that it was not a fake but rather a colossal failure.
We saw why back in March, 2004 with Is North Korea Faking It?:
The North Koreans don’t really know what they are doing, were pushed too hard to reprocess uranium fuel rods into plutonium, and left the rods in too long.
The longer you leave the rods in the reactor, the more uranium will be converted into plutonium — but the ratio of isotopes changes.
You need plutonium that is 90% of the 239 isotope to get the reaction to assemble fast enough for a nuclear explosion. More than 10% of the 240 or 242 isotopes and the reaction “fizzles.”
So it looks like what happened Monday is this:
The (at least) 3 to 4 kilos of plutonium in the North Korean bomb contained too much 240/242, which produced so many extra neutrons when the packed explosives went off that the reaction disassembled (”fizzled” or went off prematurely), resulting in a yield of less than 3% of what it should have been.
Which means that Baby Kim and his scientists are the laughingstock of all the scientists at the Pentagon, and the world community of weapons physicists. It’s safe to say that Baby Kim won’t take his being laughed at with a great deal of grace and equanimity. So it’s probably a safe bet that the lifespan of his scientists (and their families) may be soon abbreviated.
This would be very good news. Once Baby Kim kills them off, it will be hard to find replacements - and impossible to get ones smarter and more competent. Far more likely is that he’ll get ones even dumber than the ones he has now.
Even better news is that the North Korean plutonium stockpile is worthless. Too polluted with P240/242, bombs can’t be made of it, so it can’t be sold as such to other rogue states.
So don’t expect the slightest concessions from Bush and Condi. They have to pretend that North Korea is in fact right now an exceedingly dangerous nuclear threat in order to get the international sanctions on it required to prevent it from becoming such a threat one day.
But behind the diplomatic pretense there is laughter - and via discrete back channels, Baby Kim is being made aware of it. What happens when the world’s greatest egomaniac becomes a joke? This is going to be interesting to watch,