THIS week's big Bush-Yeltsin arms deal means that after decades of constructing elaborate plans and weapons for fighting nuclear war, Washington and Moscow are moving toward stripped-down, deterrence-only atomic arsenals.
It is a step toward reduced complexity that many United States military analysts - both in and outside the government - have been mulling over for years. Greatly reduced geopolitical tensions finally made it happen; now, by the turn of the century, superpower strategic nuclear stockpiles will be less than one-third their size of a only a few years ago.
"This will be seen as an enormous move forward," said President Bush at the Rose Garden ceremony announcing the agreement. "Who knows what lies out there ahead?"
Besides a numerical range limit of 3,000 to 3,500 warheads for each nation, the new pact's key feature is its restrictions on multiple-warhead missiles. Fast, accurate, dangerous, these weapons have long lain at the heart of nuclear-war fighting plans. They are both threatening and vulnerable, because they are high-priority targets.
In the end, the Russians accepted a US position eliminating all land-based, multi-warhead missiles. In return, they wangled both lower overall warhead limits than the US had proposed, and a greater reduction in the Pentagon's cherished submarine-carried, multi-warhead missile force - one-half, instead of the one-third the US had offered.
"We're talking about dramatic reductions," says Lee Feinstein, director of research at the private Arms Control Association.
For the first time, Mr. Feinstein says, the US appears to be moving in the direction of a "minimum deterrent." By this he means a nuclear force capable of riding out a first-strike attack and surviving with enough weapons to launch a retaliatory strike of its own against the fabric of the aggressor nation.
The current US and Russian nuclear forces are built around theories far more complicated than that. They're designed to be able to attack all the other nation's nuclear weapons and military command structure - in short, to fight a war, and win it if possible. This kind of planning necessitates many more nuclear weapons, and more accurate ones, than simple deterrence.
Military planners adopted the "counterforce" strategy at least in part because they were uneasy with the idea of pointing their weapons at the obvious targets: cities. But millions of civilians would perish in any kind of nuclear exchange, and "counterforce" thinking helped fuel the "we-have-to-match-the-other-guy" thinking that drove the arms race for so many years.
At a 1988 conference at the Los Alamos National Laboratory, a group of nuclear scientists and planners concluded that the US and the then-Soviets would begin to travel down this road.
"Nuclear weapons strategy is likely to move toward a `deterrence-only' policy that will place less emphasis on counterforce targeting," concluded the conference's final report.
In a prescient recent article in The Bulletin of The Atomic Scientists, former Reagan arms adviser and longtime cold warrior Paul Nitze recommended cutting US and Russian stockpiles to some 3,000 warheads. But going further to a force of a few hundred weapons, claimed Mr. Nitze, would mean planners would have to rely on the "morally unacceptable" posture of targeting exclusively civilians.
At 3,000 warheads the US stockpile is getting small enough that a number of lesser issues are suddenly looming larger in the Pentagon's calculation. For instance, at this level does it make sense to try to maintain the traditional bomber-submarine-land missile triad?
With the banning of land-based multiple-warhead missiles, and the resultant expense of the silo-based ICBM force, "it raises the question of whether you want any land-based missiles at all," notes Greg Weaver, a senior military analyst at the SAIC Corporation.
Also, any further arms control steps may have to involve the world's other declared nuclear powers - China, France, and Britain. "You really have to start bringing in the others," says Feinstein.
And the US and Russia have reached the point where the relationship between offensive nuclear arms and strategic defenses, if built, becomes complicated. According to some nuclear theorists, if a defense against nukes is robust enough to throw the other nation's retaliatory capability into doubt, a nuclear relationship could become unstable. "My guess is you can't go much lower than this on warheads and permit the other guy to do much on defense and feel comfortable," says Mr. Weaver.
Yeltsin this week agreed to work with the US and its allies to develop a concept for a global missile-defense system. A recent report by the Henry L. Stimson Center think tank, however, makes clear that Russian attitudes toward defenses are far from settled.
The study, edited by Dr. Alexei Arbatov, head of the Center for Arms Control and Strategic Stability in Moscow, says that the traditional Russian arms-control academic community, plus many in the military, oppose strategic defenses. Support for the idea comes from new Russian officials intent on building relations with the West, a loose coalition of Western-oriented academics and journalists, and "a powerful lobby in the military-industrial complex," according to Arbatov.
The still-unratified START treaty now becomes a way station on the track to Bush and Yeltsin's deeper reductions. Like START, the new agreement is to be codified in a treaty text that will be submitted to the legislatures of both nations for their approval.