Chinese Had Details of U.S. Nuclear Missiles

A 1988 Chinese military document obtained by the CIA in 1995 describes the weight, dimensions, explosive yield and other significant details of six U.S. nuclear warheads and the ballistic missiles that carry them, as well as hand-drawn sketches of the reentry vehicles that house the warheads, U.S. officials said Monday.

The material has been key to the current FBI investigation into possible espionage at Los Alamos National Laboratory, as well as investigations by congressional committees and the U.S. intelligence community.

But officials who have seen the classified material said it doesn’t contain sufficient information for Beijing to copy or construct American-style nuclear weapons. “Knowing the dimensions and the size doesn’t tell you how to build a nuclear weapon,” one said.

A chart in the Chinese-language document provides accurate data on America’s W-56, W-67, W-72, W-78, W-87 and W-88 nuclear warheads, according to U.S intelligence officials who have reviewed it.

The first three warheads date back to the 1960s or 1970s, and are no longer deployed by U.S. forces. But the W-87, which sits atop the MX “Peacekeeper” missile, and the Trident submarines’ W-88, are America’s most sophisticated nuclear weapons. The W-78 is on Minuteman III missiles and is also considered highly accurate.

The W-87 carries 10 independently targeted warheads inside its reentry vehicle, or nose cone. The W-88 has up to eight, and the W-78 has three. Together, the weapons are considered the backbone of America’s nuclear arsenal.

Among the specific details Beijing obtained for America’s ballistic missiles is what scientists call the “circular error probability,” or CEP. It describes, in yards, how accurate each missile is likely to be.

The accompanying drawings of America’s reentry vehicles are done freehand, and are not blueprints or engineering documents. The dimensions of the nose cones are written along with the diagrams, the officials said. Some of the classified details or pictures of the weapons have been published in U.S. books and magazines, and several U.S. nose cones, such as the Mark 21 that houses the W-87, have been displayed at military trade shows, according to Robert S. Norris, a weapons expert at the Natural Resources Defense Council, a Washington research group.

But the material also contained top-secret details on how U.S. scientists have used an egg-shaped, or “aspheric,” design, rather than a sphere, to help shrink the space needed for the primary explosive stage of the W-88.

One official said that the information on the W-88, while top-secret, also is printed in a classified booklet that is kept on U.S. Navy ships, at Air Force bases, and elsewhere.

“The information about the W-88 in the 1988 document could have come from thousands of places in the U.S. government,” the official said.

A Chinese official unexpectedly handed the chart and drawings to U.S. diplomats, apparently in Taiwan, in 1995. The so-called “walk-in” offered to spy for the United States, but the CIA determined in 1996 he was acting as a double agent for China’s chief spy agency, MSS.

It is still unclear if the secret details on the U.S. nuclear weapons, and the accompanying drawings, were delivered as a mistake or if they were intended to signal Washington that Beijing, in theory, could build more powerful and more accurate nuclear weapons than the relatively dated models that it has deployed. The material was contained in a much larger stack of documents that had no intelligence value.

Since nearly all the nuclear weapons on the chart were developed and built at Los Alamos, an FBI investigation soon focused on a Taiwanese-born computer scientist there, Wen Ho Lee, for possible espionage during his visits to China in 1986 and 1988. Lee has denied any wrongdoing, and a three-year FBI investigation has yet to produce criminal charges.

Officials said Lee’s improper transfer of classified computer files into an insecure computer system at Los Alamos is far more worrying than the original Chinese document. The files contain a top-secret record of America’s nuclear weapon programs and design data.

So far, the FBI has found no evidence that he provided the material to China or anyone else.

But FBI investigators who have examined Lee’s computer files have recovered drafts of letters he wrote seeking employment in the private sector from 1993 to 1995, when the bulk of the secret files were transferred. One theory now under consideration is that Lee was considering taking the files to impress prospective employers.

“The speculation is if he was leaving, he might want to take some goodies with him,” said an official who has been briefed on the investigation.

Lee apparently was able to transfer the files electronically before 1995. At that point, a new computer system installed at Los Alamos separated the classified and unclassified systems with an “air wall,” making movement of the files much more difficult.

Energy Secretary Bill Richardson will unveil new security measures at the department today, including a reorganization of security operations at the nation’s nuclear facilities.

The data and schematic drawings in the 1988 Chinese document were crucial to an assessment last month by the U.S. intelligence community, which publicly confirmed that China had acquired U.S. nuclear warhead and nose cone designs, but offered few details.

A key finding of the assessment was that the information China obtained through espionage “probably accelerated its program to develop future nuclear weapons. This . . . allowed China to focus successfully down critical paths and avoid less promising approaches to nuclear weapons design.”

The Chinese-language material also is heavily cited in a House investigative committee’s still-classified report that concludes that China has stolen secrets for virtually every U.S. nuclear weapon as well as other sensitive military technology.

The report by a committee headed by Rep. Christopher Cox (R-Newport Beach) has been undergoing a declassification review since January. Release of an unclassified version was expected this week, but officials said Monday that the release may be delayed into next week or later.

U.S. officials also have concluded that China obtained information in 1994 or 1995 that has allowed it to copy a U.S. prototype of a high-tech weapon called the “rail gun,” which uses high-intensity electromagnetic pulses to propel artillery shells or other solid objects. The technology was developed in the 1980s under the “Star Wars” defense program.

“We don’t know how they got [the information], or where it came from,” one official said. “But it’s good information, and we believe it.”

John Pike, a defense analyst with the American Federation of Scientists, said the loss of “rail gun” technology was not significant because it has not proved useful for weapons development.

“It’s extremely easy to build, but it’s extremely difficult to turn into a usable weapon,” Pike said. “We were never able to make it usable.”

In an earlier transfer of sensitive technology, officials said China obtained an “accelerometer” in 1980, a gyroscope-like device used to help guide the speed and course of ballistic missiles. U.S. officials have determined that China reverse-engineered the device and have deployed it on their own missiles.