There's a lot of uncertainly as to precisely what happened at Punggye, when North Korea set off what they described as a nuclear weapon. The seismic evidence was 4.0 or even less, while air samples are not showing anything particularly out-of-the-ordinary in terms of radioactivity, and there's no sign of a crater. It may have been the smallest nuclear blast on record (i.e., well under half a kiloton). There's little practical experience with a scam like this (setting off up to a thousand tons of conventional explosives, and calling it a nuke.) But most experts believe it was just a very small weapon (that is, not much nuclear material), or a larger weapon that did not work quite right. Both of these would be consistent with the known state of North Korean technology.

Meanwhile, living conditions, discipline and morale continue to decline in North Korea. Most worrisome is the decline in discipline in army and police units. These are guys with guns, and could lead an uprising with a chance of success.