During his first term as President of the United States, Ronald Reagan sought through his arms control positions to significantly restructure Soviet strategic nuclear forces, especially the large number of land-based intercontinental missiles. That effort has so far failed. But in the new series of negotiations expected to continue after this week's meetings in Geneva, the US administration has an even more ambitious goal: to change the nature of nuclear deterrence sharply as it has evolved over the past two decades.
The President and his supporters see this as the new hope for reducing the likelihood of a nuclear holocaust. Because of technological advances and the steady buildup in Soviet nuclear forces, Mr. Reagan says, moving toward greater reliance on defensive systems -- such as his Strategic Defense Initiative (SDI) to counter attacking warheads in space -- ``is both militarily and morally necessary.''
Other experts, including many who have worked on past arms control efforts, are just as firm in their belief that superpower stability -- which has prevented a US-Soviet military confrontation for four decades -- could be undercut if Reagan pressed ahead with what some call his ``star wars'' plan. And they warn against trying to change the basis for deterrence by forcing the Soviet Union to restructure its arsenal and strategic doctrine, rather than simply working to reduce weapons stockpiles.
``They're clearly not going to do what we want, which is to mesh their strategy with ours,'' said Gerard Smith, who negotiated the first strategic arms limitation treaty and the antiballistic missile treaty some 15 years ago. He describes the US administration as being ``in a magisterial frame of mind, trying to teach the Soviets.'' And SDI, says Ambassador Smith, is ``a new wild card in the game . . . a brooding presence'' that could make it much more difficult to achieve reductions in offensive arms.
The weight of declared opinion among scientific and military experts appears to be against the Reagan administration. Former US Defense Secretaries Harold Brown and James Schlesinger and former national-security adviser Brent Scowcroft have expressed doubts about pushing ahead rapidly with strategic defenses. So have former Presidents Richard Nixon, Gerald Ford, and Jimmy Carter.
But among other experts, there is also a growing willingness at least to reexamine the strategic equation that has led to ``mutual assured destruction,'' or the notion that each side could not avoid unacceptable retaliation if it were to launch a nuclear first strike.
``Contemporary weapons technology has made traditional arms-control theory obsolescent,'' former US Secretary of State Henry Kissinger wrote recently. ``To base deterrence irrevocably on the mutual threat to exterminate civilians would be a fateful decision.''
Former national-security adviser Zbigniew Brzezinski also argues that missile defenses could create doubts about the ability to launch a successful first strike and thereby enhance deterrence and increase stability.
Some key congressional figures favor the administration's strategic defense program as well. These include Sen. Richard Lugar (R) of Indiana, the new chairman of the Senate Foreign Relations Committee, and Rep. Jim Wright (D) of Texas, the House majority leader.
``Our objective is a stable balance and stable deterrence, and you can get that in many ways,'' said a senior administration official with the US team at Geneva. ``If we can move away from offense to defense, that's a sensible thing to do. That will be our goal at Geneva and beyond.''
Said another senior administration official influential on arms control: ``Properly planned and phased, [strategic defenses] could deny confidence in the effectiveness of an attack and therefore enhance deterrence. But our goal is moving beyond that to a thoroughly reliable defense.''
Developing and deploying such a defense would require rewriting (if not scrapping) the Anti-Ballistic Missile (ABM) Treaty, which limits each side to 100 ground-based missile interceptors and prohibits even the testing of ABM components in space.
Administration officials insist that nothing in current US strategic defense research would violate the ABM Treaty, and say it would be up to some future president to decide whether to proceed with actual deployment. Other US experts say the planned testing of such systems as Talon Gold (part of a space-based laser) would breach the treaty well before that.
``That's getting on the ragged edge of violating the ABM Treaty,'' said Robert Bowman, president of the Institute for Space and Security Studies and a retired officer who directed advanced space-programs development for the US Air Force. Those within the administration most forcefully advocating space-based defenses and a shift in strategic doctrine, said Dr. Bowman, ``are trying to make a technological end run around the Soviet Union.''
Soviet concern about moving toward new defensive systems this way -- especially in areas where the US has a clear technological edge -- was seen in a report by Soviet scientists made public as the two sides resumed talks in Geneva. The scientists expressed concern that space-based devices envisioned by strategic defense enthusiasts not only could be used as part of a nuclear first strike (by denying the other side a retaliatory capability), but might one day be used to attack targets on the ground.
Nevertheless, the Reagan administration in coming months will proceed under the assumption that advanced missile defenses leading to a change in strategic deterrence present what one senior official calls ``a very promising possibility.''