This is still a highly hypothetical question, at least for me, since my suspicion that the North Korean regime is not going to give up its nuclear weapons program in the foreseeable future is beginning to turn into conviction. Still, if there is a chance that Condoleezza Rice and Chris Hill prove themselves a visionary strategist and a top-shelf negotiator respectively and not two functionaries hoping to run out the clock by keeping the overall negotiations on life support*, this is as good a time as any to ask.
The North Korean nuclear weapons program and missile tests pushed a reluctant Japanese government into adopting what was then a highly experimental ballistic missile defense system that encompassed its Aegis destroyers. Accordingly, the justification for the introduction has consistently been the potential nuclear threat from North Korea.
Indeed, the Japanese government has taken pains to assure the Chinese government that the system will not be employed in the case of a military conflict between China and Taiwan. China has apparently chosen not to make this a political issue. In fact, the system － indeed the US national missile defense system itself － could not provide defense against the kind of massive attack that China, with its extensive nuclear arsenal, would undertake if it chose to conduct nuclear warfare against Japan. Similar assurances have not settled Russian complaints against US plans to deploy its defense system in Poland and the Czech Republic, but the Russian opposition is fueled more by geopolitical frustrations and ambitions than direct security concerns. In any case, my admittedly feeble research capacities have turned nothing by way of Russian complaints against the Japanese system. Take North Korea out of the picture, and Japan ends up with a defense system without a potential threat.
Four Kongō-type Aegis destroyers are currently being refitted, one after another, with the ballistic missile defense system. But this is a process that will take up to FY 2010. I have been unable to locate any definite plans to refit the newer Atago and its sister ship, the Atago-type Aegis destroyer Ashigara (scheduled launch 2008 March). Given budgetary constraints, refitting the pair will surely be even further off in the future.
It is better to be safe than sorry, and I have always said that any clear and present danger from North Korea’s nuclear weapons (assuming that they manage to procure a viable delivery system by them) will come in the chaos during the endgame on the Korean Peninsula. That appears to be further off in the future than in it looked the mid-90s, when hopes of an imminent North Korean collapse likely encouraged the US to be somewhat less than forthcoming than it could have been on its commitments under the 1994 Agreed Framework. (North Korea was far from blameless, but that’s another story.) Nevertheless, it would be wise for the Japanese authorities to keep a very close eye on developments in North Korea when it determines year-to-year expenditures on the ballistic missile defense program. It might, just might, save a lot of money down the line.
* I replaced the link to a Chris Hill briefing with the blog post on DPRK Studies, where I found it. The DPRK item itself is somewhat incidental to this post, but is an interesting piece of information in its own right on the last rites of the Roh regime.