September 7, 1999
SPECIAL REPORT
Spies Versus Sweat: The Debate Over China's Nuclear Advance
In This ArticleThe Breakthrough Diagram
Modern Bombs: Less Is More
By WILLIAM J. BROAD
hen American bomb makers began visiting China in 1979, they were startled by increasingly pointed questions that suggested their Chinese peers were hot on the trail of the secret to building a modern nuclear arsenal. It allows H-bombs to be made so small that many can fit atop a single missile or be fired from trucks, submarines and other mobile platforms.
China succeeded on Sept. 25, 1992, the news coming from a spy who told his American handlers that Beijing had exploded a bomb based on the miniaturization secret.
A team of scientists at the Los Alamos weapons laboratory in New Mexico set to work on a whodunit with huge implications: Was China's advance the result of espionage, hard work or some mix of the two?
Today, the debate rages on. Experts agree that spying occurred, but clash violently on how much was stolen and what impact it had on Beijing's advance, if any.
The Los Alamos team concluded in 1995 that China's stride was probably based on espionage. A report this year by a Congressional committee that made the case public went further, claiming that it would have been "virtually impossible" for China to have made small warheads "without the nuclear secrets stolen from the United States."
The Congressional report unleashed criticism from scientists inside and outside the Government who said the importance of the espionage was overstated, and that China could well have achieved the breakthrough on its own, as it insists publicly.
A review of the dispute, based on months of interviews and disclosures of weapons and intelligence secrets, suggests that the Congressional report went beyond the evidence in asserting that stolen secrets were the main reason for China's breakthrough.
The review also bolsters a point of emerging agreement among feuding experts: that the Federal investigation focused too soon on the Los Alamos National Laboratory and one worker there, Wen Ho Lee, who was fired for security violations. The lost secrets, it now appears, were available to hundreds and perhaps thousands of individuals scattered throughout the nation's arms complex.
Federal officials asked in recent days that some details about weapons design and intelligence sources not be published, and The New York Times agreed to withhold them.
For the Los Alamos team of detectives, the overall spy theory was supported strongly in 1995 when the Central Intelligence Agency obtained an internal Chinese document that included a description of the United States' most advanced miniature warhead, the W-88. Revealing for the first time their top evidence in the case, the document's secret contents, Federal officials say the Chinese text cited five key attributes of the warhead, including two measurements accurate to within four-hundredths of an inch.
But the critics, who are also revealing new information, insist that Beijing, even if it spied, made the miniaturization breakthrough on its own, pursuing it for at least 13 years, from 1979 to 1992.
The prowess of Chinese scientists, American experts said, is suggested by a camera they built for photographing nuclear blasts, which was far better than a similar one made by the United States.
"They don't need any help from us," said Harold Agnew, a past Los Alamos director, visitor to China and Federal intelligence adviser. "They're just curious, as we are curious about them."
Some secret specifications of the W-88, an American miniature hydrogen bomb, that were found in a Chinese document.
The New York Times;
Illustration by Mika GrondahlDeconstructing the damage wrought by espionage is an imprecise art that mixes inference, evidence and deduction. In the vacuum between what is known and what is suspected, personal, partisan or institutional bias often rushes in.
The debate over Chinese spying has been blurred by issues that include Republican distaste for President Clinton's China policy, accusations of racial bias in the investigation and fears among scientists that the uproar is prompting security measures so tight as to damage work, morale and recruitment.
As in most spy cases, the evidence is open to interpretation.
Several critics familiar with the Chinese document obtained by the C.I.A. said that its description of the American warhead was not by itself sufficient to build a miniaturized warhead.
The Energy Department official who supervised the Los Alamos inquiry, Notra Trulock, agreed with this assessment but said the information was secret and had never been mentioned in any public document or Internet posting. Anyone who had it, he and his team reasoned, must have also obtained access to a much broader range of secrets about the warhead's design.
In addition, Trulock said in an interview, knowing the approximate size and shape of the components provided a road map to Chinese bomb makers, probably allowing them to skip years of preliminary testing.
Trulock added, however, that the Congressional committee was too categorical in its report, which was based in part on his testimony.
"When I testified, I used the appropriate caveats to express uncertainties in our evidence and our conclusions," said Trulock, formerly the Energy Department's intelligence chief. "We typically said: 'Probably this. Probably that.' " The committee, he said, "made judgments" about the centrality of spying in China's breakthrough.
Representative Christopher Cox, a California Republican who was chairman of the committee, defended the work of his staff of 47, which included no one with nuclear design experience. The panel, he said in a lengthy interview, drew largely on Clinton Administration witnesses for its expertise. The conclusion that espionage allowed Beijing to skip decades of research, he said, was an appropriate one, based on the Government's own evidence.
"Judgment matters," he said, responding to Trulock's criticism. "We don't know everything to a certainty. The question is what is more likely than not."
In the interview, Cox expressed surprise when told of the depth and breadth of China's interest in the miniaturization secret. He also played down the idea, cited by Federal skeptics of Chinese spying, that most of the world's nuclear powers have figured out the secret of miniaturization.
Can China, Cox asked, "develop it indigenously because France did? That is a stretch. It's almost apples and oranges."
The Secret: America Shrinks an Atomic Match
From the dawn of the nuclear age, miniaturization has been an obsession of weapons designers.
The world's first atomic bomb, designed by the Los Alamos laboratory and detonated in the New Mexico desert in July 1945, was an awesome but cumbersome affair. A lump of plutonium the size of a softball was surrounded by a much larger ball of high explosives that was five feet wide and made up of 32 explosive charges and 64 detonators. Big as a car, it could not have fit into a small airplane, let alone a missile.
In 1952, American physicists made an important breakthrough: the H-bomb. Roughly a thousand times more powerful than the first atomic weapon, the hydrogen bomb was a two-stage device. Inside its dense casing, an atomic explosion -- called the primary -- worked as a match to kindle an even more powerful detonation by the bomb's hydrogen fuel, which was known as the secondary.
Size was an issue from the start. The first H-bomb stood two stories high and weighed 82 tons. It would be militarily useful only if it could be shrunk, and over the next few years, the country's best physicists set out to do just that.
After considerable trial and error, they figured out that they could obtain the same kind of explosive power from a smaller package. A main breakthrough centered on the large, heavy atomic match. By shaping its plutonium fuel into an ovoid, roughly like a watermelon, scientists were able to drastically shrink the size and number of the explosives that triggered the nuclear blast.
After at least one flop, the radical idea roared to life in July 1957 in a nuclear explosion in the Nevada desert, according to Chuck Hansen, author of a detailed history of America's early nuclear efforts. It had taken the United States a little more than five years to move from the first H-bomb to its miniaturized cousin.
The development had profound implications for the cold war's nuclear competition.
Shrinking the atomic trigger from something roughly the size of a washing machine to something smaller than a football allowed weapons designers to put thermonuclear arms atop small missiles that could be launched from submarines or mobile platforms like trucks. Arms would no longer be confined to bombers or silos in the ground.
The advance meant weapons could now be carried, quite stealthily, closer to enemy shores and could be made safer from attack. It also meant warheads could fit into the cramped spaces of narrow nose cones, which streaked faster to Earth than blunter shapes and were less buffeted by winds during the fiery plunge, making them more accurate.
The first warhead in the new generation of weapons, the W-47, was less than half the size of the bomb that leveled Hiroshima but up to 80 times more powerful. In 1960, when the first Polaris submarine put to sea, each of its 16 missiles was armed with a W-47.
The weapons continued to evolve, and by all accounts, the apex was reached in the 1980's with the W-88, one of the most deadly weapons in the American arsenal.
The warhead, made for submarines, first went to sea a decade ago and is considered quite powerful for its small size. The precise size is secret. But at least eight W-88's can fit atop the Trident D-5 missile, which is less than seven feet wide.
Since Trident subs have 24 missiles, a single submarine can carry up to 192 of the thermonuclear arms.
Today, American submarines on patrol in the Atlantic carry the small warheads. And the Navy is adding them to its Pacific fleet, so in the next few years the W-88 is likely to be aimed at China.
The Chinese: Late to Start, Quick to Excel
China was late in joining the nuclear club, but showed considerable skill when it did.
Beijing detonated its first bomb in 1964. The tricky design was based on uranium, like the Hiroshima bomb, but saved costly fuel and made the bomb lighter, increasing its military value.
Sidney D. Drell, a Stanford physicist and Clinton Administration adviser, writing in "China Builds the Bomb" (Stanford University Press, 1988), called the feat "enormously impressive." Beijing's first hydrogen bomb came just 32 months later.
By comparison, the step from nuclear to thermonuclear took London 66 months, Moscow 75 months, Washington 87 months and Paris 103 months, said Robert S. Norris of the Natural Resources Defense Council, a private group in Washington that monitors nuclear arms.
China set off just 6 test blasts to get to the H-bomb stage, versus 31 for the United States. The low number was typical. While developing at least six types of weapons, Beijing over the decades conducted relatively few nuclear tests, 45 in all, versus 1,030 for the United States.
The evidence strongly suggests that China, in its first phases of missile building, had no idea how to shrink thermonuclear arms. According to "China's Strategic Seapower" (Stanford University Press, 1994), the warhead for the submarine missile deployed by Beijing in the 1970's weighed 1,300 pounds, more than twice the old American W-47, suggesting that the Chinese were still using a spherical atomic match to ignite H-bombs.
China's land force was modest. Starting in the 1980's, it deployed about 20 missiles that can now reach anywhere in North America, each topped by a single warhead that can unleash a force equivalent to up to five million tons of high explosives. That is about 300 times stronger than the Hiroshima bomb.
The big warheads are not particularly accurate, but they fit China's professed war doctrine -- to fire nuclear arms only in retaliation. The big missiles can, if necessary, hit a city.
China's interest in building smaller weapons was spurred, in part, by the United States' development in the late 1970's of a high-accuracy design known as the Missile Experimental, or MX, that bristled with 10 warheads. Though meant primarily to unnerve Moscow, the weapon also worried Beijing, which quickly grasped that its handful of big land-based missiles looked like sitting ducks that could be destroyed in a first strike of precisely aimed H-bombs.
Beijing's unease grew as the American Navy in the late 1970's unveiled plans for a new submarine-launched missile nearly as unerring as the MX and bearing an even more powerful warhead -- the W-88.
American intelligence agencies knew little about China's nuclear program and modernization plans, if any, before President Richard Nixon's visit to China in 1972. But the military ties that followed the Nixon diplomatic initiative opened the door.
By 1979, American nuclear arms designers and security experts were starting to visit their Chinese peers, weapons labs and Lop Nur, the sprawling site in China's western desert where prototype nuclear weapons were detonated.
From Los Alamos alone, at least 85 scientists and officials made trips from 1979 to 1990, according to Robert S. Vrooman, a former C.I.A. officer who at the time directed counterintelligence at Los Alamos.
Top visitors included Dr. Agnew, the past director of the weapons lab; Danny B. Stillman, its head of intelligence; and George A. Keyworth 2d, a physicist who later became President Reagan's science adviser.
The benefits were judged to far outweigh the risks that arms scientists in informal settings and conversations might, by accident or design, give away secrets. And indeed, the Americans learned much.
"This was a huge intelligence game for the United States," said a United States official who spoke on the condition of anonymity. "At the beginning we knew zip about China."
One discovery was that parts of the Chinese program were quite advanced, including technologies for bomb development.
"They have excellent facilities, some better than ours," said Dr. Agnew, who in 1979 and 1982 was among the first visitors.
For instance, he said, the Chinese were able to peer into fiery blasts with an advanced camera known as pinex, revealing details to aid warhead development.
The American version of the device had one axis, he said, the Chinese version two, doubling its usefulness. "It's much better," Dr. Agnew said.
The American visitors also learned much about what China lacked. From a barrage of inquiries over the years, it became clear that Beijing was eager to learn everything it could about shrinking the atomic trigger. The questions were regular, increasingly pointed and never answered, American officials said, insisting that Beijing got no secrets that way.
But in one case, investigators became suspicious about an American scientist at the Livermore weapons lab in California who in 1979 had talked with Chinese scientists.
The suspect, born in Taiwan, never confessed. But some Federal investigators, in an investigation code-named Tiger Trap, feared the scientist had compromised not only the design of the W-70, a neutron bomb, but the secret to making small atomic triggers.
Weapons experts say that the crucial insight of the watermelon shape can be communicated with a few comments, a hand motion or a simple drawing on the back of an envelope, although years of computing, calculation, experiment and factory labor are then needed to turn the idea into nuclear blasts.
"The real challenge is not in the design, it's in the manufacturing," said Houston T. Hawkins, head of international security studies at Los Alamos.
For example, he said, plutonium, one of the most complex metals known to science, is difficult to cast because of its odd ways of reacting with other metals and materials.
"It's a strange beast," Hawkins said of the dense metal that fuels most atom bombs.
Copyright 1999 The New York Times Company
