Dolohov wonders what is up in North Korea. This response being long, I've put it in my journal rather than in a pile of comments. For the purposes of this post, I'm going to assume that there actually was a nuclear test today, and that this isn't just a normal earthquake accompanied by opportunistic PR.
First up: batshit crazy versus careful planning. Is North Korea crazy, or does this meticulous planning indicate deep cunning? Well, both. I mean, evaluated as a person, there is some metric by which every country is crazy. The term doesn't really apply. I'm not really sure what human terms would apply -- North Korea is whimsical, perhaps (That always-readable bloodthirsty racist
Gary Brecher puts it best: Kim Jong Il is impulsive, but the people who work for him are psychotically dedicated and talented. I think that adds up to something like whimsy). In a centralized country, meticulous people can be dispatched on crazy and whimsical errands -- no matter how strange or changeable the leadership is, long-term projects can and do still happen. Doesn't Mr. Kim's new opera open sometime soon?
Here is Central Question #1: Did North Korea have more to fear from internal or external enemies? As with all questions in foreign relations, no objective answers please -- it's the subjective that matters.
From a certain perspective the nuclear test is rational. If you assume that Mr. Kim is more scared of the US than of his own people, in fact, trading sanctions for nukes makes perfect sense. He has just guaranteed that he will never again need to worry about invasion, and the only cost was a bit more mass starvation and cannibalism in the provinces. It's a confident move, but not by any means a bad one.
Now for China. China's number one worry in every respect is anything bad happening to North Korea. This is not because they like North Korea -- even when they were setting up Kim Il Sung, the record is pretty clear that they hated and distrusted him (Gaddis' recent history, We Now Know, has some great declassified info on how the various big Communist leaders got along back in the 50s and 60s. You can call this revisionist history, but since Gaddis wrote the history he's revising, I think he's entitled.). Rather, this is because China is in the middle a very ugly economic puzzle of managing urbanization and controlling labor flows; a million refugees flowing in from Korea are really the last thing they need. So a political, economic, or military collapse in North Korea is to be avoided at all cost, they figure. Their nigh-hysterical diplomatic response to this nuclear test, combined with no meaningful action, means that China answers CQ1 the opposite way that North Korea does. Of course, they've also got some related concerns about nuclear ubiquity, but I'll get to those later.
South Korea is in exactly the same boat as China. Not every day that that happens. South Korea generally seems to believe that the most dangerous thing the North could do, worse than an outright war in fact, would be to collapse. They're probably right: North Korea would lose a war in a matter of days (though possibly destroy Seoul in the process), but a million refugees shambling through the DMZ would wipe out the South Korean economy and possibly political system overnight. As Morocco's "Green March" proved, a few hundred thousand civilians are at least as dangerous as an army against a civilized enemy.
Why now for the test? North Korea may have been trying for some time. They dug the test chamber more than a year ago, and held some sort of public event there then (or so the satellite photos say). It may be that it's just taken them this long to get the damned thing to go off. I don't think it's related to South Korea's recent UN victory -- SK is practically an ally to the North, because since they answer CQ1 "internal" they will do whatever is necessary to prop up the Kim regime.
What all of this adds up to is that basically only the US really cares much about the North Korean nuke as such. Everyone else is more concerned that the response to it -- sanctions, even military action -- might destabilize North Korea. There are, though, a few regional stability implications that China and the US cannot ignore. A North Korean nuke, particularly if it doesn't draw down serious consequences, could embolden a lot of the other local players who would like nuclear weapons. Many local states are "screwdriver powers" -- countries that have exercised their NNPT rights to get to "one screwdriver-twist away" from nuclear weapons. Taiwan, Japan, Indonesia, and Australia come to mind; there are probably others. It is easy to imagine, say, Taiwan deciding to go nuclear, and everyone else going nuclear because they don't want to be the last one in the club still defenseless if things go to hell. This sort of nuclear-ubiquity scenario is inevitable in the long term, but in the short term is still scary as hell to status-quo powers (diplomacy's word for "countries with nicer stuff than their neighbors"). Countries concerned with this sort of thing will be extra-nasty to North Korea (to warn others) and extra-nice to, eg, Taiwan (to reassure them that there's no need to do anything hasty). This is very bad news for China, as that is the polar opposite of the strategy it would choose otherwise. This is why the entire executive leadership of China is currently skipping the annual Communist Party Conference to chat with the entire Japanese executive branch, which prior to this month would have been beyond unthinkable.
The crowded nature of the area means that nearly every local power has a territorial, sovereignty, or maritime dispute with every other country in the area. There is one possibly oil-rich set of islands claimed by no fewer than six different countries. While the notion of a war breaking out may seem remote to us, it is definitely not remote to the locals. Asia's Cold War is on the horizon, and it just got worse. Perhaps Taiwan will play the role of Berlin; Indonesia may star in the local remake of the Cuban Missile Crisis. Absent serious diplomatic talent, the next half-century could see a dozen shooting wars between nuclear powers. That is enough to put this all in longer-term perspective. The US really ought to be propping up and encouraging China (and India and Russia) to exercise some goddamn adult supervision on the diplomatic side, but that doesn't seem to be happening. Asia needs its Kennan, its Kissinger, its Acheson, and its Stevenson rolled into one right now. And speaking of jobs no sane person would want... how about that new Secretary General? If I were he, I'd be pondering having a good disqualifying sex scandal right about now.
Finally a brief polemic of a political nature. Given that the US is unable or unwilling to do anything actually, you know, helpful in East Asia, perhaps it should bloody well get the hell out? Just maybe? Let Taiwan and South Korea internalize their own security costs for a while (if they can even be troubled to; they can bloody well kiss and make up with Japan if they can't). The long-term US interest in sitting nearly two hundred thousand troops in the middle of a multipolar nuclear security funhouse, generating ten times as much resentment as actual security, is pretty damned thin and getting thinner. The simple Cold War truth is they're not there to defend themselves or others -- they're too few. They're there to get killed and force the US into a wider war if things go to hell. Is that really desirable now?