A Powerful Barrier To Future Nuclear Tests

The Comprehensive Test Ban Treaty President Clinton signed last week is more than a symbolic break with the nuclear past. It is a practical step toward a safer future.

For good reason, much discussion of the CTBT has been cast in historical terms. Mr. Clinton is redressing what President Eisenhower described as the "greatest disappointment" in 1963, when the ban on atmospheric nuclear tests drove them underground. He rightly characterized that as a "step," though a major one. It removed nuclear poisons from children's milk but created no real impediment to the further development and refinement of nuclear arms.

In contrast, the CTBT - completely banning nuclear explosions of any size, in any place, forever - not only completes a bipartisan arms-control quest spanning more than 40 years, but it also helps wall off real nuclear dangers today and henceforth.

The treaty's formal entry into force is likely to be delayed by India and perhaps others. Even so, the treaty is immediately effective. In voting for it at the United Nations, and now in affixing their signatures, virtually all the world's countries are confirming that nuclear testing is unacceptable. This worldwide consensus will be a mighty barrier against any further nuclear tests, even as we continue to work to make the treaty fully binding in law.

From now on, one major effect of the test ban will be to help prevent the spread of nuclear weapons to more countries. Without testing, it is much harder to make a weapon small enough to load on an aircraft, fit atop a rudimentary missile, or conceal in a terrorist's luggage. So the test ban backs up other agreements, including the Nuclear Non-Proliferation Treaty, to keep shrinking the number of states with a usable nuclear option.

Permanent moratorium

What about the existing nuclear-weapon states? To be sure, all five are now observing a voluntary moratorium on tests. But that has held - and expanded to France and finally China - only under the spotlight from the test-ban negotiations in Geneva. The test ban locks it in place.

Here the treaty's major value will be to rule out any new qualitative race in nuclear weaponry. Through computer modeling, subcritical experiments, and other techniques, we can keep existing weapons safe and reliable without tests.

That is true especially where the number of different kinds of weapons, as well as the overall total, is falling pursuant to US-Soviet/Russian arms-control agreements and, in the case of the United Kingdom and France, through voluntary steps.

But it's a far different thing to develop new kinds of weapons that can be confidently relied upon for deterrence or war-fighting. That, absent testing, we cannot do.

So, for example, a test ban in the late 1960s would have prevented a multiple-warhead technology under which combined US and Soviet missile warheads subsequently soared from around 2,700 to more than 17,500, or more than a sixfold increase. That included such innovations as the Soviet SS-18 missile, with 10 immense warheads, which many thought made the US vulnerable to a first strike.

Preventing deadlier nukes

With testing, other major breakthroughs would be possible - a number of them in the realm of so-called "directed energy" weapons to extract even greater military effects from smaller packages - and so make nuclear arms still more deliverable, flexible, and attractive to use. But now, no matter what the political future holds, such options are out of reach. And China, which is modernizing its nuclear force, is sharply limited in what it can do.

The CTBT also has security benefits outside its immediate bounds. Like last year's victory in making the Nuclear Non-Proliferation Treaty permanent, the test ban gives us a clearer view of the secure nuclear future in which we can safely continue the disarmament process that is already reducing US-Russian nuclear arsenals by more than two-thirds. It sustains the momentum toward an ever smaller security role for nuclear arms.

The test ban means less nuclear risk in the world's least stable regions, constrained nuclear- weapons innovation, and smaller weapons stockpiles. As a country that has conducted well over 1,000 nuclear tests - hundreds more than any other country - the US has an obvious interest in arresting everyone's climb up the nuclear learning curve, including its own, through the CTBT.

John Holum is director of the United States Arms Control and Disarmament Agency.