On US Wish List: Ability to Detect Nuclear Arms

AT a recent meeting with reporters, Air Force Chief of Staff Gen. Merrill McPeak began ruminating on the United States military's lack of ability to detect nuclear weapons hidden by terrorists or rogue states.

``Can we develop an airborne sniffer that can locate nukes with a high degree of sensitivity?'' wondered the Air Force leader. ``We can't find nuclear weapons now, except by going on a house-to-house search.''

Worried that the assembled scribes would take this remark too seriously, General McPeak emphasized that he was only thinking out loud. But the fact is that obtaining just such a capability is now high on the Pentagon's wish list, as it readies for a new post-cold-war mission: counterproliferation.

In the past, the United States government has focused on nonproliferation, trying to keep materials and technology for nuclear, chemical, and biological weapons out of the hands of North Korea, Iraq, and other suspect nations. The counterproliferation push means that the Defense Department will pay more attention to organizing and equipping for defense if, or when, nonproliferation fails.

This month, the administration announced a counterproliferation policy that includes measures from developing better detectors to new weapons for attacking nuclear sites to better intelligence analysis. Counterproliferation is an area that ``ought to be a growing preoccupation of this department,'' said a defense official at a briefing on the policy.

The importance of this policy shift is emphasized by the situation in North Korea. Published reports indicate that the Central Intelligence Agency (CIA) has found that Pyongyang has one or two nuclear bombs.

Meanwhile, North Korea still refuses international inspections of its nuclear sites. It has not backed off from threats that it will pull out of the Nuclear Non-Proliferation Treaty. But United Nations Secretary-General Boutros Boutros-Ghali said Sunday after visiting North Korea that the dispute may yet be resolved. ``There is the political will'' to solve the problem, he said at a press conference in Beijing.

Defense officials have indicated that they have few options besides diplomacy and economic sanctions with which to deal with the North Korean situation.

A preemptive attack on Pyongyang's nuclear program is out of the question: The US does not have weapons capable of blowing up deep concrete bunkers with assurance, and it would be almost impossible to locate all bombs and nuclear materials.

The North Korean nuclear arsenal, produced by a long-standing national effort with dispersed and hardened sites, would be the most difficult kind to root out. For the short term, the Pentagon wants capability to deal with the relatively easier task of countering nations or groups that might obtain a few loose nukes secretly, perhaps from stocks of the ex-Soviet Union. Need analysis

Nonnuclear bunker-busting warheads are one item officials say they must develop. Analysis on what might happen in a bombing raid on nuclear weapons is lacking. Detection and tracking equipment must be improved, in particular, so officials can judge if nuclear threats are real.

US national labs have been working on nuclear ``sniffing'' equipment for years. Some effort has aimed at equipping NEST, the Department of Energy's special antiterrorist nuclear-search team founded in 1975.

NEST teams are based at Andrews Air Force Base, outside Washington, and Las Vegas, Nev., among other sites. It is known that they have detection equipment capable of fitting in vans, helicopters, and aircraft, but their full abilities are classified information.

Gamma rays and neutrons emitted by the fissile materials in nuclear weapons could theoretically be vulnerable to detection by nuclear sniffers. The emission of both, however, can be slowed or stopped by lead and concrete shielding.

``Obviously, we're trying to figure out ways around that,'' says Bob Andrews, associate director for nonproliferation, arms control, and international security at the Lawrence Livermore National Laboratory. Tagging technologies

Lawrence Livermore has yet to receive new orders or more money under the Clinton counterproliferation program. But Mr. Andrews says many of their tagging technologies, developed for possible use in arms-treaty verification, could be used to inventory and keep track of the worrisome ex-Soviet arsenal.

Deployment of NEST-like detectors with US military troops is one option under consideration in the Pentagon.

The counterproliferation policy also calls for continued development of theater antimissile systems. A CIA estimate holds that North Korea, for example, might be able to marry nuclear warheads with intercontinental ballistic missiles capable of hitting the US within 15 years.