The following comments are by Patrick M. Morgan, Professor of Global Peace and Conflict Studies at the University of California, Irvine.
Morton Halperin's discussion of the nuclear dimension of the US-Japan relationship is a stimulating analysis of a subject not often frontally addressed. Since Japan has no nuclear weapons or announced plans to obtain them, and since the US no longer has any nuclear weapons on its ships visiting Japan, the nuclear dimension of the alliance is seldom considered. The Halperin paper carefully explores possible future scenarios under which nuclear weapons could spread and is an imaginative and thoughtful proposal for avoiding the more dangerous possibilities.
The review of US objectives in maintaining nuclear weapons is concise yet complete, as is the analysis of the possible options for US policy, in the abstract, vis-a-vis nuclear weapons in the future. However, the suggestion that the US is firmly entrenched in the first of these options is perhaps a bit misleading. Clearly the US has not renounced all its nuclear 'weapons, reserves the right to use them first, and suggests that it might use them against any state that used WMD (Weapons of Mass Destruction). It also plans to maintain a large stockpile of nuclear weapons components, giving it the option of creating a much larger arsenal on short notice. But it is also clear that the US has been trying to stigmatize nuclear weapons in some ways. It has agreed to huge cuts in its nuclear arsenal, to negotiate still further cuts, and to halt nuclear testing. It is investing very heavily in advanced conventional forces for military contingencies around the world, trying in part to reduce to nil the likelihood it will ever need nuclear weapons to achieve its military objectives. It has convened them into weapons of last resort in some ways, in its own policies and in NATO. It has withdrawn them from Korea and has largely abandoned a nuclear threat to North Korea. It is the bulwark of very vigorous nonproliferation policies under the UN or NATO, alongside its own policies, which are much more intrusive than in the past. Thus the US policy is closer to a blend of the first two options.
Next, it is undoubtedly important that the US continue to be resist any nuclear proliferation in Northeast Asia, and Japan would be a good candidate for this if the entire regional security situation disintegrated. However, the impression the paper creates - despite explicit language to the contrary at times - is that Japan is poised to develop nuclear weapons if US policy moves in the wrong direction (with a reported debate in the US as to which direction that would be). In fact, the obstacles to Japan becoming a nuclear power are much greater than this implies, particularly in view of the newly refurbished alliance. Japan does not like the idea of nuclear weapons and missiles so close by, in Korea, but it has put up with nearby nuclear weapons (Russian, Chinese) for years - relying on US nuclear deterrence - so it is unlikely to react quite differently now. And Japan has been careful to try to avoid antagonizing the entire region with its military polities, so it would not readily take the one step guaranteed to overturn all regional security considerations and arrangements.
In the same vein it is hard to see why, as the paper suggests, Japan might now feel more concerned about a possible non-nuclear US response to a nuclear attack on Japan. Japan lived for years with the fact that a US response to such an attack from the Soviet Union would be so risky as to be of dubious credibility, something that would be much less so now in responding to such an attack from China or North Korea. So the problem should be no larger than it was and is probably smaller. If the US did stick to a non-nuclear response it would almost certainly attempt, through its conventional forces superiority, to eliminate the offending regime, which should therefore be just as deterred as when facing the threat of a nuclear riposte.
Halperin's view that US openness to using nuclear weapons to respond to a nuclear attack on its allies is good for encouraging nonproliferation may be correct, but it does not seem like the best guide for policy. It would seem better to leave ambiguity as to how the US could respond, while continuing to contemplate a non-nuclear but highly effective response if possible, and trying to get its allies to see this as beneficial. (The Flexible Response debate all over again.) In addition, it seems likely that such a decision will always be based on the situation and not on a predetermined policy. The US should plan on: responding without nuclear Weapons if this is feasible; exploring whether this is acceptable in principle to US allies, even if they are attacked with nuclear weapons); seeing if this is acceptable to other states, and whether they would also accept a nuclear response to an initial breach of the nuclear taboo; seeing what the public says at the time.
As for moving toward cooperative security arrangements for Northeast Asia, this is a fine idea, as is the proposal that preliminary talks begin. But my impression, in talking with policy makers and various analysts, is that this sensible course of action is not being employed, even privately, because in various ways it is politically unacceptable. For North Korea, such discussions imply an enlargement of the coalition that it now confronts. For China, the discussions would invite just that reaction by the North and therefore would suggest that, like others, China expects North Korea to collapse. And Japan's involvement would be a good way to arouse ROK and DPRK concerns about its future influence in the area. Such informal and formal discussions are needed, as are the cooperative security management efforts that could emerge, but apparently they can only be pursued as very preliminary in nature (at best) - with the idea of laying the groundwork for a future time when conditions are more propitious. And the most important condition here will likely be emerging evidence that the North is about to collapse.
It may be that the best route to wider discussions about regional security management will be to eventually enlarge the current four-party talks about the peninsula, particularly since Japan and Russia have been angling to be included in them from the start. And talks like these will certainly be needed when the time comes to implement unification. Whether gradual progress in these kinds of discussions could culminate in a nuclear free zone would then be explored at a later time. To try to seek one now will just multiply the complications involved in the negotiations, both externally and at home for each party, so it should probably be treated as a very late stage objective. The ultimate objective mentioned in the paper, a Northeast Asian Cooperative Security Organization, is highly desirable but will take considerable adjustments, particularly by China, to bring about. It will have to remain a goal for the long term.
Finally, as the paper indicates, keeping the US alliance with a unified Korea is a good idea and is probably feasible. But retaining more than skeletal US forces in Korea, without any serious threat to Korea, is probably impossible, even under the quite imaginative arrangements suggested in the paper to ease the concerns of the neighbors. After all, if all the great powers agree to unification and to a decent relationship with the new state, that would be a major contribution to regional peace and security. They would certainly expect to see US forces then depart; in fact, this seems likely to be a minimal demand for Chinese or Russian support for unification. Otherwise, the US gets what it wants, but what do they get? It would also be difficult to sell a continuing US military presence to Congress and the public, when the threat is gone, and there is Korean nationalist sentiment to consider as well. An arrangement might be possible under which the forces are gradually rather than immediately withdrawn, but their indefinite presence seems unrealistic.
