Keep Cutting Nuclear Weapons

FOUR recent cases in Germany of attempted diversion of explosive nuclear material from Russia are only the most visible aspects of a much larger problem. Against the background of Russia's political and economic instability, the Russian nuclear arsenal, with 30,000 warheads and hundreds of tons of fissile explosives, is the world's greatest source of nuclear dangers and may be so for decades.

Cutting back the Russian arsenal through further cuts in Russian and US weapons is the most effective way of dealing with these dangers. It is far preferable to the risks and costs of maintaining large US nuclear forces to deal with Russian contingencies. More urgent are new measures to stem the current leakage of fissile material from Russia before it becomes uncontrollable. Dangers include transporting nuclear-weapons capability to unstable areas south of Russia and undermining the nonproliferation regime. The approaching April 1995 conference to extend the Nuclear Non-Proliferation Treaty also confronts the Clinton administration. The White House must articulate for the first time its concept of the long-term future of nuclear weapons. Many non-nuclear nations want to know what the US will do with its nuclear weapons before they commit to never owning them.

President Clinton's United Nations speech on Sept. 26 and his meeting with Russian President Boris Yeltsin Sept. 27 will provide valuable opportunities to address these issues. Mr. Clinton can have great impact on controlling the Russian arsenal in the coming crucial months and play a decisive role in assuring continuation of the NPT.

To meet these urgent requirements, the president should emphasize ``far-reaching and irreversible nuclear disarmament'' as the theme of his UN speech and of his talks with Mr. Yeltsin. The two presidents agreed in January that reduction of nuclear weapons should be made irreversible. They established a joint group to make this practical. It is time to further these efforts.

Far-reaching and irreversible disarmament can best be achieved through three measures:

* Further deep cuts. The US should propose a protocol to the START II treaty to reduce the level of US and Russian strategic warheads significantly below START II levels and, once this supplementary agreement is concluded, pursue negotiations among all five nuclear-weapons states to reduce their forces to minimum deterrent levels.

* Making nuclear-arms reductions permanent. The US and Russia should agree that arms reductions under the START treaties and subsequent agreements will be made irreversible by dismantling all nuclear warheads withdrawn from operational deployment. Fissile material in these warheads should be stored where it can be internationally monitored.

* A US-Russian agreement to end production of fissile material for weapons. The US has agreed. Russia is holding out. This agreement is more feasible because of progress toward US-Russian understanding on monitoring the production of three remaining Russian plutonium-production reactors until they can be replaced by other energy sources. The agreement would make it impossible to make new weapons-grade fissile material to replace that handed over to internationally monitored storage. It would give impetus to Clinton's initiative to conclude a global multilateral agreement.

More urgently, Clinton and Yeltsin should agree next month to implement two measures on the problem of leakage of fissile material from Russia:

First is a comprehensive, reciprocal exchange of information on all Russian and US stockpiles of already fabricated warheads and weapons-grade fissile material, whether in production plants or in storage. There is no effective Russian system of accounting for nuclear weapons or fissile materials. An exclusively Russian system, even if possible, will not resolve the problem. Reciprocal data exchange is the answer.

Second, the US and Russia should establish a reciprocal system of monitoring storage sites for stocks of warheads and fissile materials based on the system now in use under the Intermediate-Range Nuclear Force Treaty. The bilateral monitoring system would be superimposed on existing custody arrangements. The presence of US monitors would help inhibit the main proliferation dangers posed by Russian stocks: forcible seizure, theft, illegal sale, or use of stored fissile materials to make more weapons.

The two presidents should establish a target time-frame of six months for completion of data exchange and one year for installation of a full monitoring system. Each should agree to appoint a single senior official with full responsibility for negotiating and implementing these programs, now divided among many government agencies. We should firmly lock this free-swinging barn door before it opens the way to a tragedy. The Opinion/Essay Page welcomes manuscripts. Authors of articles we accept will be notified by telephone. Authors of articles not accepted will be notified by postcard. Send manuscripts by mail to Opinions/Essays, One Norway Street, Boston, MA 02115, by fax to 617 -450-2317, or by Internet E-mail to OPED@RACHEL.CSPS.COM.