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from the San Jose Mercury News/Knight Ridder Newspapers, 1999-Apr-14, by Dan Stober:

Miniaturized warhead has potential to change nature of Chinese military power

If espionage has allowed Chinese scientists to take a virtual look inside the W-88, the miniature thermonuclear warhead of the Trident missile, what have they seen?

An unusual configuration of shapes and materials that has shrunk the size of the once-mammoth hydrogen bomb so drastically that eight of them now fit atop one missile, launched from a submarine. This miniaturization of the bomb, most fully developed in the W-88, is perhaps the most strategically significant development in nuclear weapons since the invention of the atomic and hydrogen bombs.

Possession of this technology may allow China to follow in the footsteps of the other major powers by placing multiple warheads on their missiles, vastly increasing their destructive power.

But experts caution that even with this technology, China remains so far behind the United States in terms of nuclear might that the nuclear equation between the two states will remain virtually unchanged for years to come.

Any nuclear strike on the U.S. would trigger an overwhelming counterattack of thousands of warheads, according to Michael Swaine, the director of the RAND Center for Asia-Pacific Policy in Santa Monica. ``What would the advantage be to China?'' he asks.

The W-88, designed at Los Alamos National Laboratory in New Mexico, is the U.S. military's newest thermonuclear warhead. It is the latest in an evolutionary line of warheads that were reshaped to fit into the narrow confines of the cone-shaped ``re-entry vehicles'' that carry the explosives to their targets.

Over the years, U.S. weapons designers have reduced the size of thermonuclear weapons from refrigerator-sized devices to something closer in size to a bag of golf clubs.

Chinese scientists reportedly tested a miniature thermonuclear warhead in the mid-1990s, after receiving secret data on the U.S. warheads from the Los Alamos National Laboratory in the 1980s. Why didn't China develop them earlier, on its own?

``Things go slowly in China. These programs are very drawn out,'' said Stan Norris, a nuclear specialist at the Natural Resources Defense Council in Washington. ``The Chinese have postured themselves as actually saying to the rest of us, `We can get by with a small stockpile. We don't need the tens of thousands (of nuclear weapons) you guys built and bankrupted yourselves in the process.'''

Possession of the miniaturization technology may allow China to put several warheads on one missile, either on land or on a submarine, expanding the number of targets without greatly increasing the number of missiles. Or single warheads could be placed on small, mobile missiles towed behind trucks, valuable because they can be hard for an enemy to find and destroy.

What does it mean if China now has the capability to manufacture such weapons? In the near term the effect will probably be minimal, according to several experts.

``It means that they are in a better position to threaten their neighbors than they have been in the past, although I think the danger has been overstated,'' said Bruce Bueno de Mesquita, an international policy specialist at the Hoover Institute. China, which already has a limited nuclear force, doesn't need more advanced weapons to deal with Vietnam, Korea or Taiwan, he said.

In the long run, he said, a more sophisticated Chinese nuclear missile force may cause worry in Japan and Russia. Japan has no nuclear weapons, and Russia cannot afford to upgrade its force.

The immediate danger to the United States is almost nonexistent, according to Swaine, the RAND expert.

Even with modern warheads, China's missile force remains antiquated, he said, and needs a long preparation time before launch. The Chinese missiles -- some of which already have the capability of striking the American West Coast -- have purposely been a deterrent force, intimidating enough to keep other countries from attacking, but not useful in a first strike against another nuclear power, Swaine said.

China is in the midst of a major modernization of its military. ``But we don't see any evidence that the Chinese have embarked on a full blown effort to arm their missiles with multiple warheads,'' he said.

``The leap in logic that people are making from small nuclear warhead to MIRV (multiple warheads) to national danger is an enormous leap,'' Swaine said.

MIRVs were first deployed by the U.S. aboard Minuteman and Polaris missiles, amid much political controversy in the 1960s as a way to overwhelm Soviet missile defenses and attack Soviet missile silos.

``They provided the ability for one silo's worth of missiles to attack many silos of missiles,'' said Ted Greenwood of the Sloan Foundation in New York, who published the definitive unclassified history of MIRVs in 1975.

The W-88 is the newest of the U.S. nuclear warheads, and when placed on the Trident submarine-launched missile (built in Sunnyvale by Lockheed Martin Missiles & Space), forms the premier American weapons system.

The basic design features that allow miniaturization of warheads can be found in the warheads of all U.S. strategic missiles: the Trident (W-88, W-76), the MX (W-87) and the Minuteman (W-62, W-78).

The basic breakthroughs in design came in the 1950s at Lawrence Livermore National Laboratory, and made their appearance in the warhead for the Polaris, the first submarine-launched missile, in 1963. ``Virtually all modern thermonuclear weapons of all nuclear powers derive from this advance, including all MIRV explosives,'' John Nuckolls, a former director of Lawrence Livermore, wrote in 1988.

According to numerous interviews with U.S. weapons designers over the last two years, the miniaturization of the warhead has been achieved by employing shapes and nuclear materials in ways that differ dramatically from the familiar diagrams of hydrogen bombs that have been published in textbooks, magazines and newspapers for decades.

Inside the W-88 and other missile warheads are two explosives, one known as the ``primary'' and the other the ``secondary.'' The primary is a plutonium fission bomb used to trigger a fusion explosion in the secondary -- a nearby capsule of radioactive hydrogen.

The first plutonium bombs, such as the one dropped on Nagasaki, were spheres, and they have been portrayed that way in the popular press ever since. But in 1957, Livermore scientists found a way to squash the spheres into egg-shapes or ovals, the better to fit into the pointed nose of the re-entry vehicles.

The secondary, the hydrogen capsule, is almost universally portrayed as a cylinder, as it is in some bombs dropped from airplanes. But for missile warheads, Livermore scientists changed the shape from a cylinder to a sphere in 1958, a change that has been a staple of warheads since.

Three bombs in one At the same time, the physicists surrounded the spherical hydrogen capsule with a layer of bomb-grade uranium, which also explodes, dramatically increasing the ``yield'' of the weapon. Thus the physicists built three bombs in one: plutonium, hydrogen and uranium.

The configuration is known as an ``Oralloy thermonuclear weapon.'' (Oralloy is the name given to bomb-grade uranium.) The process is also referred to as ``fission-fusion-fission.''

Edward Teller, the physicist who founded and guided the Livermore lab, was said to be ecstatic when the configuration proved successful in a nuclear test on a South Pacific atoll in 1958. ``Edward was on Cloud Nine, exclaiming in his thick Hungarian accent, `Wonderful, wonderful,''' Carl Haussmann, a senior scientist, recalled before his death last year. ``It's been a slow evolution,'' said a physicist familiar with the design of the miniature warheads. ``They've tweaked it here and there and increased the output. People make it sound like this (the W-88) was some radical new idea. But if you thumb through the reports, (the warheads) all look the same.''