Two Sides of the Nuclear Sword

By BRUCE VAN VOORST

"Strategic stability is the holy grail to defense planners," says former National Security Adviser Zbigniew Brzezinski. Hopes of achieving national military superiority disappeared in the radioactive clouds over Hiroshima; today nuclear deterrence is built on the shaky assurance that either the U.S. or the Soviet Union could absorb an attack and still devastate its enemy in response. By this logic, a first strike would never be attempted.

But the $2.4 trillion Reagan military buildup is producing weapons that seem designed to upset the strategic balance and give the U.S. a nuclear advantage over the Soviet Union. Experts warn that weapons systems such as the Strategic Defense Initiative and the just-unveiled Stealth bomber could make the world more dangerous by prompting a hostile Soviet response. Other weapons that were first introduced by the U.S., such as cruise missiles and multiple- warhead ICBMs, have been copied by the Soviets and now pose a greater threat to Americans.

Just how destabilizing such systems could be was illustrated last week when the Army conceded that SDI could severely threaten the Soviet Union's satellite system. Both the U.S. and the U.S.S.R. depend heavily on low-orbit satellites for military intelligence, navigation and communications. The Star Wars antimissile weapons, sitting in space, could easily be turned against Soviet satellites traveling in predictable orbits. Such a prospect is as unacceptable to the Soviets as it would be to the U.S. Former Secretary of Defense Robert McNamara describes SDI as so destabilizing that he believes the Soviets would "be justified in shooting the system down, even in peacetime."

Soviet generals might someday be equally tempted to launch a pre-emptive attack on the radar-avoiding B-2 Stealth bomber, which former Defense Secretary James Schlesinger boasted "makes obsolescent $200 billion worth of Soviet air defenses." Traditional wisdom holds that U.S. bombers are not first-strike weapons, since they would take up to eight hours to reach their targets. But if the B-2 can fly over the Soviet Union undetected, the Soviets could reasonably fear a sneak "decapitation" attack on their leadership. In that case, editorialized Aviation Week magazine, "this new U.S. deterrent might serve to incite them, not reassure them."

Strategic advantage can vanish quickly as the Soviets steal or copy military technology and turn it against its inventors. McNamara suggests that "it takes the Soviets on the average only four years to catch up" to U.S. advances -- and then the weapons may pose more of a threat to Americans than to the Soviets.

The U.S., for example, already has both air- and sea-launched cruise missiles, and plans to build thousands of a new, advanced, low-observable "stealth" version. Because they fly slowly compared with ICBMs, American cruise missiles are not by themselves considered a first-strike weapon -- like bombers, they would take hours to hit targets deep inside the Soviet Union.

But Soviet cruise missiles represent a far-reaching threat to the U.S. Half the American population and industrial capacity sit within 150 miles of the ocean coasts, where cruise missiles launched from Soviet submarines could strike quickly and unexpectedly. The U.S. has virtually no defense against such missiles, particularly when the Soviets also employ stealth technology. The threat is compounded by the difficulty in negotiating a cutback in cruises: they are so small and portable that their numbers would be almost impossible for either side to verify, and conventionally armed missiles cannot be distinguished from nuclear weapons.

In the current strategic-arms talks, the U.S. is already attempting to reduce a destabilizing threat it introduced without sufficient reflection a decade ago. The U.S.deployed MIRVs (multiple independently targetable re-entry vehicles), which enabled a single U.S. Trident I missile to carry as many as eight nuclear warheads. The rationale -- similar to that of Stealth -- was to penetrate Soviet antiballistic-missile defenses, which were themselves considered destabilizing because they threatened the American ability to retaliate effectively. But the Soviets responded with huge ten-headed SS-18 missiles that can destroy the U.S. land-based deterrence. These so-called silo busters offer a frightening incentive for a first-strike attack that, says defense analyst Sidney Graybeal, "makes them extremely destabilizing."

On the checkerboard of action and reaction, stability is often in the eye of the beholder. Albert Carnesale, a widely respected nuclear strategist, wryly observes that "weapons are destabilizing only if they are your adversary's." The difference between an offensive first-strike weapon and one useful just for defensive retaliation "lies in intent only," says Carnesale. Yet often weapons are introduced largely because the technology is available, rather than to meet essential strategic requirements. As George Bush considers how to proceed with SDI, Stealth and the START talks, the standard he must apply is the quest for stability.