WASHINGTON -- In 1995, a Chinese spy posing as a defector walked into an undisclosed U.S. Embassy and handed over a stack of secret Chinese documents, including an explosive 1988 memo that contained classified information on six nuclear warheads in the U.S. arsenal.

That single document, 20 pages in length, summarized Chinese knowledge of American nuclear weapons, proving that China had penetrated the highly secret program. It became the Rosetta stone for a burgeoning espionage investigation.

It led to allegations that Taiwanese-born computer scientist Wen Ho Lee had passed secrets to the Chinese from his base at the Los Alamos National Laboratory. It triggered perhaps the most dramatic security crackdown in the history of the nation's nuclear weapons labs. And it spawned heated accusations that the Clinton administration was lax, not only in its surveillance of Chinese intelligence activities but its response once those activities were exposed.

That China surreptitiously obtained U.S. nuclear secrets is no longer in doubt. What is hotly disputed is the military significance of the information. Some officials contend that U.S. national security has been severely compromised, while others insist that most of what the Chinese obtained was worthless, outdated or widely available at a good public library when China obtained it.

A major interagency damage assessment released April 21 by intelligence agents from the CIA, FBI, Pentagon, Energy Department and State Department was similarly inconclusive.

"China obtained by espionage classified U.S. nuclear weapons information that probably accelerated its program to develop future nuclear weapons," the intelligence assessment concluded. However, reviewers also stated, "We cannot determine the full extent of weapon information obtained. We believe it more likely that the Chinese used U.S. design information to inform their own program than to replicate U.S. weapon designs."

Moreover, the damage assessment said, "To date, the aggressive Chinese collection effort has not resulted in any apparent modernization of their deployed strategic force or any new nuclear weapons deployment."

Nevertheless, warned James R. Lilley, a U.S. ambassador to China during the Bush administration, such caveats should not diminish the seriousness of the security breaches.

"I think they have obtained an awful lot. How much they can absorb and use against us is not clear, but we're beginning to see some disturbing signs," said Lilley, a China expert at the American Enterprise Institute for Public Policy Research. "Of course you should be concerned, but I would not be hysterical about it."

Unclassified report expected

This week, the House Select Committee on U.S. National Security and the People's Republic of China is expected to release an unclassified version of its report detailing its findings on Chinese espionage.

The report is not likely to quell the debate over the significance of the data obtained by the Chinese, but its authors say it will confirm that the Chinese have been diligently seeking the nation's most sensitive nuclear secrets, despite insistent denials by Beijing.

"Facts aren't inflammatory. Facts are facts," said California Republican Rep. Christopher Cox, chairman of the select committee. "These are facts that are completely known to the People's Republic of China, so it cannot complain."

The Cox committee, formed almost a year ago by then-House Speaker Newt Gingrich in response to an outcry over alleged missile-technology transfers to China, concludes that the Chinese:

Obtained classified information on seven nuclear weapons systems, from sketchy data on the antiquated W-56 warhead to detailed design data on the diminutive W-88, the second-newest warhead in the U.S. arsenal.

Obtained conceptual information on a neutron bomb from a scientist at the Lawrence Livermore National Laboratory, then tested a version of the weapon in the 1980s.

Obtained some conceptual information in the 1990s on a rail gun, a giant cannon that was being developed in the 1980s as a missile-defense system but never put into use.

Obtained in 1980 a missile-guidance part known as an accelerometer, a technology which remains under the control of State Department export restrictions but is widely available commercially for domestic use.

The report also criticizes the Clinton administration for lax security controls on launches of commercial U.S. satellites in China, launches that led to the improvement of Chinese ballistic-missile capabilities. And it details the export of about 600 high-performance computers by U.S. firms that could be used to simulate nuclear weapons blasts.

White House aides "are not going to be able to spin their way out of this," a House GOP aide said of the report.

Mysterious memo

Virtually all the information on Chinese acquisition of U.S. nuclear weapons secrets came from that one 20-page document provided mysteriously by a purported Chinese defector who was later found to be working for Chinese intelligence.

It is unclear why such a memo, written by Chinese officials, would be turned over to the United States with the Chinese government's blessing, but intelligence officials say they have no reason to doubt its authenticity.

Sources in Congress, the administration and the intelligence community agree that by far the most sensitive information obtained by China involved the W-88 -- a warhead, developed in 1988 at New Mexico's Los Alamos National Laboratory, that rests on top of the Trident II submarine-launched missile.

Most of the other information in the so-called "walk-in" document can be found with a diligent search of the public literature, said government sources.

"That's not to say everything in the walk-in is identifiable [in public sources], but outside the 88 it's not like you open [the document] up and say, 'My God, the whole world is in this,' " said a source familiar with the Cox report and the 1988 document.

Even the information on the W-88 is incomplete and lacks schematic drawings or blueprints that could lead directly to the warhead's replication, U.S. officials said.

The W-88 information included the overall shape and size of the warhead and the configuration of some internal components, enough information to indicate that the Chinese understand the technique U.S. scientists used to pack multiple W-88 warheads onto a single mobile missile, a government official said.

Still, two officials familiar with the 1988 document said such information would be of only marginal value to nuclear weapons scientists seeking to duplicate the W-88's design, though other nuclear weapons experts said the information would save Chinese scientists valuable time and money by steering them clear of developmental dead ends.

'Saved them a lot of money'

The other serious breach involved information gleaned from the Lawrence Livermore lab in California in the 1970s and early 1980s, concerning the W-70, or neutron bomb.

The low-yield warhead was designed to kill people through enhanced radiation emissions but to spare buildings by minimizing the size of the explosion. It was never fielded in the U.S. arsenal.

"The neutron bomb information could have saved them a lot of money," said Tom Thomson, a senior nuclear weapons physicist at Lawrence Livermore. "It cuts down on the trial and error. If you short-circuit the [design] process and go into production earlier, you can spend the money you saved on real bullets," not research and development.

Some sources have said the W-70 data may have been critical to the Chinese in other ways. They could have coupled the warhead's very precise nuclear trigger -- the initial or "primary" explosion that sets off the "secondary" thermonuclear blast -- with the "secondary" of the W-88, sharply boosting the size of the explosion.

The W-88's secondary has the most destructive power of any warhead its size in the U.S. arsenal.

In combination, the two components would create an extremely potent mobile warhead.

But others say such assertions are pure conjecture. Indeed, said one senior administration official, the information gleaned by the Chinese on the neutron bomb primarily dealt with the concept of an enhanced radiation warhead.

He compared it to information on the neutron bomb readily accessible in a detailed article published by Scientific American in 1978, about the time the neutron bomb espionage is believed to have started.

The significance of information on four other nuclear weapons -- the W-56, W-62, W-78 and W-87 -- is the subject of fierce debate. The Cox report concluded that the Chinese learned critical design information about those weapons, and an intelligence official, speaking on condition of anonymity, said China obtained highly classified information on the warheads' form and function that is unavailable in the open literature on nuclear weapons.

But other senior government officials familiar with the report and the 1988 document said the Chinese learned only the size, weight and explosive force of the warheads, along with the missile systems upon which they are mounted.

Errors repeated

While that information is technically classified, it can be gleaned by weapons experts from public sources, such as arms control treaties, and is widely available on the Internet and in public libraries.

Indeed, some of the information may have come from those sources. The officials said some of the Chinese data on warhead sizes and explosive yields repeated mistakes made by public sources, such as the Natural Resources Defense Council's Nuclear Notebook.

"To suggest that this is some deep, dark secret is ridiculous," scoffed Robert S. Norris, a nuclear weapons expert who compiles such data for the NRDC. "The whole thing is becoming ludicrous."

Some government officials were equally dismissive about two other revelations in the Cox report: that the Chinese obtained an accelerometer in 1980 and information on a rail gun.

An accelerometer -- which simply measures acceleration -- has many uses in a ballistic missile, from guiding it to its target to ensuring that the nuclear warhead explodes on contact with a solid object, such as a bunker. But it is primarily used as a safety device, measuring the acceleration of a missile as it shoots skyward, then arming -- or turning on -- the warhead at a certain speed. That way, the warhead would not be armed if a missile misfired and fell back to earth.

Such technology is also used in everything from earthquake detection to automobile air bag triggers. Though the most advanced accelerometers cannot be exported without a special waiver, even the most sophisticated 1980 accelerometer is now commercially available, said Jeffrey Rybak, a vice president at Oceana Sensor Technologies, a Virginia Beach, Va., accelerometer maker.

"The Chinese would have been able to get that technology anywhere," Rybak said.

Because the Chinese are only now developing a new generation of missiles, weapons experts say, it is doubtful that they would equip them with 1980 accelerometer technology. The advanced Dong Feng-31 intercontinental ballistic missile is expected to be deployed in 2003.

Beyond gunpowder

On the other hand, rail guns are far more sophisticated, so sophisticated that U.S. engineers have never been able to turn them into viable weapons.

In the 1980s, President Ronald Reagan's Strategic Defense Initiative funded multiple efforts to develop rail guns, giant cannons that use electromagnetic waves instead of gunpowder to launch projectiles. But the force of the explosion made the guns untenable weapons systems, because they needed expensive repairs after a few firings.

The most advanced rail gun was developed at Lawrence Livermore. Its inventor, John W. Hunter, hoped to turn it skyward and use it to launch payloads cheaply into space, but he failed to garner investor interest. Iraqi President Saddam Hussein tried to develop his own version before the Persian Gulf war, but that, too, did not work.

"They've been around for a long, long time, rail guns, linear electric motors. It's all in the open literature," Thomson said. "There may be some engineering tricks to it, but there's no real secret."

What makes the rail gun revelation significant is when it came. A government official said the Chinese obtained the information from a Midwestern location in the mid-1990s, placing Chinese espionage efforts on President Clinton's watch.

Although the military significance of the security breaches is contested, even administration officials concede that the sheer quantity of information obtained by the Chinese points to lax security and inadequate enforcement of export controls. Clinton's desire to maintain cordial relations with China may have created a climate that discouraged counterintelligence efforts and eliminated a potential spy's fears of reprisal, critics say.

Wen Ho Lee fell under FBI suspicions in 1996, after agents linked information on the W-88 found in the 1995 document to Lee's trips to China in 1986 and 1988.

But Lee's government computer was not searched until March, giving the computer scientist time to delete evidence from more than 1,000 secret weapons files he inappropriately transferred from Los Alamos' classified computer network to his unclassified office computer. For more than two years, those highly classified files were accessible to the outside world.

Lee -- who maintains his innocence -- has not been charged with a crime, though he was fired from Los Alamos for violating security regulations.

"Does it do harm? Of course it does harm," said Lilley, the former ambassador to China. "I wouldn't get into the business of mocking it."

The White House has agreed to implement nearly all of the Cox committee's 38 recommendations, including tightening security and counterintelligence at the nuclear labs and heightening export controls.

"A rational response is not to argue, 'That's not an important thing, so let's ignore it,' " said Ken Flamm, a Pentagon official in the Clinton administration who holds the Dean Rusk chair in international affairs at the University of Texas.

"That gets you down a path that is very dangerous."

Pub Date: 5/23/99