A plutonium device should produce a yield in the range of the 20 kilotons, like the one we dropped on Nagasaki. No one has ever dudded their first test of a simple fission device. North Korean nuclear scientists are now officially the worst ever.
This may explain why reports indicate a second test site has activity.
Given that some of Pakistan's tests nearly a decade ago were fizzles, we may have extra indications of the cooperation between Pakistan and North Korea.
If North Korea's test was a dud, and given that North Korea should have known that the nuke could be a dud, what does this tell us? Were the North Korean scientists convinced they had the problem licked? And so this tells us the scientists truly are the worst ever? Or could it tell us that North Korea has very limited raw materials for tests and so risked a single test rather than use up scarce nuclear material in an effort to hide failures amidst a number of tests?
Either explanation is good news.
After two high profile failures, perhaps the North Koreans should demonstrate something a little more reliable--like a new crossbow design with a cheap laser pointer duct taped on to help aiming.
Actually, with two failures, will the North Koreans risk another high profile failure with a second try at a nuke test?
And if this fails, could North Korea try another simpler method of inspiring fear? Like firing off some simple artillery and rocket rounds at Seoul?
Regardless, there should be no do-overs allowed. Treat this as if it was a successful test and put the screws to North Korea so the regime collapses and dies. If the test was a failure, consider that a bonus so we know that North Korea can't go all nuclear crazy in response. Because one day, if we don't stop them, they will succeed in going nuclear.
UPDATE: Growing evidence (tip to NRO) this fizzled big time--maybe just the conventional explosives meant to trigger the nuclear chain reaction actually went off. Treat this as a warning and act as if it worked. Squeeze North Korea until they collapse. One day they'll get it right if they survive long enough.