This covers well-trodden ground, so prepare to be bored. If I seem to have made up my mind on things, that's just the way I write. If you see more posts here in the future under this general topic, you are more likely than not to see me changing my mind on some of the things you see here and in future posts. Join me in thanking the powers that be that I am not the one making decisions.
The North Korean nuclear test, if it is found to have been a technological success and North Korea refrains from conducting further tests, will remove much uncertainty and result in a new equilibrium for its relations with its neighbors. The same cannot be said for its internal affairs. If North Korean authorities are unable to maintain the status quo, change will come, likely very quickly. The Five should be prepared for such a contingency, and make that fact known. In the meantime, the threat to regional security should be forestalled by allying Japanese fears of a more substantive North Korean threat.
The two major fears of analysts in the region are:
1) a nuclear attack or threat thereof by North Korea, either as part of a last-ditch effort to avoid regime change or a final act of destructive defiance; and
2) a nuclear arms race triggered by Japan's reaction to fears over 1). (Proliferation is America's big fear, and a global concern, but that's a different animal).
The key nation in calculations over both these fears is Japan. Conventional wisdom in Japan says that the development of the North Korean nuclear weapons system has mainly targeted Japan. Conventional weapons already stand poised to attack South Korea, and more specifically Seoul, en masse. The United States is too far away. So Japan is a convenient target for a nuclear attack/counterattack on the alliance. You may argue that Japanese fears are excessive, but the argument is at least plausible argument. And US emphasis on non-proliferation suggests that US priorities, at least in the near future, do not converge totally with Japan's. Thus, Japan's perceptions of its security needs and the degree to which they are being met should be seen as the key determinant of East Asia's nuclear future (in contrast to that of the global community as a whole).
Given this context, it was no surprise that the hawkish Shoichi Nakagawa, newly Chairman of the LDP Policy Research Council (making him one of the three top non-cabinet party officials), raised eyebrows at home and abroad when he opined to the effect that, given the situation with North Korea, discussion itself of nuclear weapons would do no harm. (Aside: the original WaPo blurb "Japan to Reexamine Ban" was somewhat exaggerated. Will WaPo do a retake on this article, now that Mr. Nakagawa himself has issued a disclaimer that he "made his statements from the perspective that we should discuss how to protect Japan without having nuclear weapons of our own"? Probably not; the media hates to backtrack.) Indeed, nobody doubts that Japan, as well as South Korea and Taiwan, all have the technological capacity to develop a nuclear bomb very quickly. But Japanese officials from the prime minister down staunchly deny that Japan has any intention of seeking a nuclear weapon on its own. As things stand now (more on that later), a firm commitment from the United States to retaliate massively and overwhelmingly should keep any calls for nuclear armament on the fringes.
But what if such US threats are of no effect, however credible they may be? That is the point of the destructive defiance hypothesis, more colorfully rendered by some Japanese commentators as "horobi no bigaku(aesthetics of dissolution)" a la Hieke Monogatari or perhaps more appropriately, imperial Japan's notion of ultimate Ichioku Sougyokusai(100 Million Total Death on the Battlefield).
I think that is a remote possibility. All indications are that Kim Jong-il and his top cadre do not have likes of the delusional visions of global grandeur of the Nazis, or even the Five Peoples' Mutual Harmony daydreams of WW II Japan. Their game is survival, and would more likely than not decline to resort to a line of action that would take down their families and relatives (and thus bloodlines) with them and bring enmity to the Korean people for that act. However, it is imprudent to rely on such conjecture alone. Besides, it would not preclude North Korea from wielding its nuclear weapons as a threat. Thus, it is of prime importance that North Korea not be allowed to go any further in developing a nuclear weapons system that includes a missile-deliverable capacity.
A scenario that would ensure such deterrence would include a commitment from the US that it will conduct a preemptive surgical attack on any sites that show activities of a future missile launch or any sites, and a commitment from China, South Korea and Russia that they will stop all subsidies to North Korea in the event of North Korean activities to such end. Without credible joint action to stop North Korea from progressing to the next stage, i.e. full-fledged nuclear power status, Japan will feel increasingly threatened as North Korea pushes ahead with its nuclear weapons system program. A North Korea with nuclear bombs that could be delivered only by conventional aircraft or ships is one thing; a North Korea with antiballistic missiles ready to deliver a nuclear warhead at an instant's notice is another.
Such assurances from fellow members of the Five must be complemented by assessment of the transition problems in the implosion scenario of the inevitable endgame, and a commitment to coordinate their efforts have the added benefit of making the implosion scenario of the inevitable endgame far easier to manage.