THE NUCLEAR SECURITY OF JAPAN AND SOUTH-KOREA - A JAPANESE VIEW

Japan has long enjoyed the US nuclear umbrella, the primary nature of which is a retaliatory nuclear deterrent-not a deterrence based on nuc lear first use but a deterrence of an adversary's first use of nuclear and other mass-destructive weapons. The US nuclear shield for South K orea has evolved from a NATO-type nuclear first use to a retaliatory n uclear deterrent because of an increasingly favorable conventional mil itary balance vis-a-vis North Korea. A nuclear umbrella as a retaliato ry nuclear deterrent does not necessarily require the placement of pro tector's nuclear weapons on the soil of the protege or the vicinity of its border. Considering the specter of nuclear devastation, what is r equired to maintain some credibility in the retaliatory nuclear commit ment is a possibility of the protector's nuclear response and an under standing of that possibility by the adversary. Occasional references t o nuclear commitments to Japan and South Korea by the US government wo uld be sufficient to make an adversary understand possibility of a US nuclear response. Thus the new US policy, withdrawing all non-strategi c nuclear weapons from East Asia and the Western Pacific but retaining a redeployment option for nuclear-armed Tomahawk SLCMs, would not ser iously damage the credibility of the US nuclear umbrella for Japan and South Korea. US SLBMs deployed continuously in the Western Pacific an d nuclear Tomahawk SLCMs that would be operational if needed, would pl ace mute pressure on Russia, China, and a nuclear-armed North Korea to subordinate their international behavior to the goal of preventing th e use of nuclear weapons. The US high-tech conventional weapons, by at taining extreme accuracy and the capability to discriminate a wide ran ge of targets in attacking, have acquired considerable counter-force c apabilities previously achievable only with nuclear weapons. Many in t he US defense community seem to believe that the new military capabili ty can serve as a credible deterrent to a regional power's use of weap ons of mass destruction. However, a guarded observation requires that the US should not rule out a nuclear option completely in a regional c onflict, since the deterrent effect of conventional threats is inheren tly less clear than that of nuclear threats. First, it may be difficul t to let a potential adversary understand the devastating power of US high-tech conventional weapons. Their destructive power is not derived from their explosiveness but from their accuracy and discriminating c apability. Thus, efficacy of high-tech conventional weapons depend lar gely on the capability to locate and attack critical targets of advers aries. US intelligence capabilities, therefore, matter very much. But no country in the world can know precisely the degree and extent of US intelligence capabilities. Second, doubt remains that the threat of c onventional retaliation alone is frightening enough to prevent a risk- prone adversary from using nuclear and chemical weapons. The penalties or costs associated with attack from conventional weapons tend to be perceived as manageable. Third, high-tech conventional deterrence, to be sufficiently compelling, would be inhibitively expensive. Fourth, e mphasizing high-tech conventional capabilities may carry the risk of c ausing nuclear and chemical weapon proliferation. Countries that oppos e US interests but lack the financial and technological capacity to co unter US high-tech weapons may find it advantageous to develop nuclear and chemical weapons to offset American conventional superiority. In short, it seems to be premature to depend upon US high-tech convention al weapons as the only tool for regional deterrence. Imposing various constraints on the use of nuclear weapons does not endanger the US mis sion of extending nuclear deterrence. Rather, carefully crafted measur es for controlling and banning of the use of nuclear weapons would red uce the danger of nuclear weapons, thereby easing the nuclear deterren ce mission. First, it is advisable for the US and other NWSs to adopt the policy of no-first-use of weapons of mass destruction, rather than one simply of nuclear no-first-use. A nuclear first-use threat is pro bably required to contain chemical and biological weapons. The second is to institutionalize collective, uniform, and legally binding condit ional negative security assurances by the five NWSs to NNWSs. Third an d as an alternative to the global negative security assurance regime, Japan and South Korea should work for establishing a NWFZ covering Jap an and the Korean peninsula. In addition to the US nuclear umbrella, a NWFZ would add one more nuclear security assurance to Japan and South Korea: legally binding negative security assurances from China and Ru ssia. One important condition for a successful NWFZ is that Japan and South Korea (or a reunified Korea), with US assistance, would have to maintain adequate conventional military capabilities vis-a-vis their n eighboring militarily powerful countries so that the US nuclear umbrel la could continue to function as a retaliatory deterrent. If either So uth Korea or Japan, even in combination with US forward deployed force s, were not to succeed in maintaining a conventional military balance against its potential adversary, the function of the US nuclear shield would change from retaliatory to first use, thereby necessitating the end of the NWFZ and the deployment of US tactical nuclear weapons on its own soil.