A Comprehensive Test Ban (CTB) treaty to end all nuclear explosions is being negotiated in Geneva. A "zero yield" treaty would be a great step forward toward reducing proliferation problems. The five nuclear weapons states favor such a CTB for the future, but have attached conditions to it. China wants a review in ten years to allow for the possibility of "peaceful nuclear explosions." The other nuclear weapons powers also want conditions that will perpetuate weapons design capabilities. However, the conditions could undermine the stability of the CTB in times of crisis, and create serious new global tensions and dangers in the long term.

The United States, Russia, France, Britain, and China each possess nuclear weapons design laboratories and apparently plan to continue their use after a CTB is in place. In the U.S., the Science Based Stockpile Stewardship (SBSS) program would maintain both nuclear warheads and weapons designers indefinitely, as the accompanying article shows. Like the U.S., France is building a large laser fusion device for laboratory testing of thermonuclear components. Russia has announced a stockpile stewardship program similar to that of the U.S. China could continue design work under a provision which if incorporated into the CTB would allow for a review of the "peaceful nuclear explosions" issue ten years hence. This could be China's way of maintaining the design capability that the SBSS program would give to the U.S., Britain, and France.

A Comprehensive Test Ban treaty that does not restrict nuclear weapons programs and is not accompanied by a closing of all test sites leaves the treaty and other nonproliferation agreements vulnerable. The United States intends to keep the Nevada Test Site open indefinitely as a condition for acceding to the zero yield CTB. Though the U.S. Department of Energy (DOE) has stated that the lack of full-scale underground testing will be a major impediment to any new warhead design,¹ it could nevertheless design new weapons using the SBSS facilities and keep the test site ready to explode them for final testing before certification and production. Keeping the test site in a state of readiness to undertake full-scale nuclear tests on short notice would allow the U.S. to introduce new weapons into the arsenal very quickly and easily once these designs have been mostly completed on computers and in lab facilities. The capabilities of modern facilities to accomplish complex designs tasks were demonstrated by the success of the Boeing 777, a large commercial aircraft designed mainly by computer and wind tunnel experiments.

Weapons programs in the U.S. and other countries will employ thousands of people to build, run, and maintain laboratory and testing facilities. It is widely recognized that the SBSS program was the price paid to the nuclear weapons laboratories to support or at least not actively oppose a zero yield CTB. But the same large weapons bureaucracy created by the program will constitute a strong lobby which could exert pressure to withdraw from the CTB in times of crisis.

The maintenance and expansion of nuclear weapons programs also has implications for disarmament efforts. Russia and probably China lack the funds to greatly expand their nuclear design infrastructure. Moreover, the U.S. has a long-standing and extensive program to share nuclear weapons data with Britain. The U.S. and France recently signed a secret agreement to share the data that would come out of their nuclear weapons laboratory and computer simulation efforts. The immense financial and technical advantages of the three western powers combined with this secret agreement may provide incentives to China and Russia to test in order to make up for their lack of advanced facilities, and could cause them to hold up progress on disarmament on other fronts.

These vulnerabilities of the CTB are similar to the current crisis affecting two existing treaties, the Anti-Ballistic Missile (ABM) treaty and the Second Strategic Arms Reduction Treaty, START II. In the U.S., many powerful voices advocate a partial or total abandonment of the ABM treaty and the deployment of a ballistic missile defense system, popularly called "Star Wars." But Russia lacks the money to develop such a system, much less to deploy it. Many in Russia view the Star Wars program as a strategic threat because they fear that such a system, were it to become fully operational, could allow the United States to both launch a first strike against Russia and to defend itself against a retaliatory attack. It was precisely on this point that President Gorbachev rejected President Reagan's proposal for nuclear disarmament during their Reykjavik summit in 1985.

Therefore, Russia has linked its ratification of START II to U.S. adherence to the ABM Treaty. In such a situation, the potential technical capability of the Star Wars system overrides the stated motives of the United States ( namely, to counter putative missile threats from countries such as North Korea and Iran.

It is worth noting that the pressures for the U.S. to withdraw from the ABM treaty have increased since the 1980s, when the Star Wars program began receiving large sums of money. Similarly, a Comprehensive Test Ban which includes a built-in weapons design lobby with a vested interest in justifying its long-term existence invites danger in the years ahead.

Another possible reaction to the SBSS program by Russia, and possibly even by China, would be to participate in a form of "cooperative stewardship." A recent official workshop held at Los Alamos on cooperative stewardship discussed the advantages of the five nuclear weapons states working together whenever possible. Such cooperation could have its advantages in the context of implementation of Article VI of the Non-Proliferation Treaty (NPT), under which the weapons states are obliged to end the arms race and pursue nuclear disarmament in "good faith." But cooperation to indefinitely maintain their nuclear arsenals, as the weapons states seem inclined to do, will not likely be viewed in a positive light by many non-nuclear states or by non-signatories to the NPT, notably Israel, India, and Pakistan. These last three countries are unlikely to accede to the NPT or abandon their own nuclear weapons programs under such circumstances.

A breakdown of the CTB in a time of crisis due to internal lobbying pressures may even cause the NPT regime to unravel. While that risk may appear small at the present time, U.S. pressures on the ABM treaty and the concomitant failure thus far of Russia to ratify START II are stark reminders of the possibility. Few could have predicted the current impasse at the time the ABM or START II treaties were signed.

The dangers of an unstable nuclear test ban can be avoided with a few simple commitments that should be incorporated into the implementation of a zero yield CTB. The nuclear weapons powers should:

• permanently renounce all nuclear testing, including "peaceful nuclear explosions," and close down their test sites;

• unequivocally renounce design of nuclear warheads;

• stop construction of new laboratory testing facilities;

• refuse to allow any escape clauses such as "subcritical" underground testing or modification of the CTB to allow "peaceful" nuclear explosions in the future.

A zero yield CTB with these minimal provisions would avoid future unpredictable conflicts and instabilities. As the remaining superpower both militarily and economically, the U.S. should show the way by being first to announce support for these steps.