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.
October 14, 2006: The UN voted to impose sanctions on North Korea, making it illegal to provide material used to make weapons. However, because of pressure from Russia and China (who both fear a flood of refugees coming across their borders if the North Korean government collapses), there is no enforcement mechanism. China and Russia did not want the sanctions to do anything to actually hurt North Korea, or anger its government.
October 12, 2006: The North Korean nuclear bomb test sparked another debate in South Korea over the current "Sunshine Policy" towards the north. But beneath all this rhetoric is the reality that hardly anyone in South Korea wants to actually unify the country. This would create an enormous social upheaval, political trauma, and economic disaster for most South Koreans. But it is considered bad manners to discuss this openly, so it rarely is. Instead, it's more fashionable to blame the United States. Never underestimate the power of fashion.