Boom or bust

Arms Control Wonk has the low-down on the NK nuclear test. It appears the test was probably a failure, though it could have also been a bluff. The size of the blast was less than one kiloton, but putting together up to 1000 tons of high explosives to bluff a failure seems remote, a successful first-time plutonium blast should yield 10-20 kilotons.
So the best guess now is a failure.
There's talk that they might try another test in a few weeks, but unless they are testing a different design that seems useless. Having an arsenal of nukes with a 50/50 chance of going off gives deterence a bad name.