THE SOVIETS AND THE SUMMIT : Non-Nuclear Missiles Emerge as Post-Treaty ‘Super Weapons’ : Arms control: The Pentagon turns with enthusiasm to technology using conventional explosives.

As President Bush and Soviet leader Mikhail S. Gorbachev prepare to approve the outlines of a major nuclear weapons treaty, the Pentagon is turning with new enthusiasm to developing non-nuclear missiles that now appear to represent the future of superpower weaponry.

Among the new “super weapons” being eyed is a cruise missile--code-named “Tacit Rainbow”--designed to fly long distances and circle repeatedly if necessary before homing in on enemy radar units’ electronic signatures and destroying them with a non-nuclear blast.

Defense planners have even higher hopes for a missile called the Long-Range Conventional Stand-Off Weapon, which from distances of 2,000 miles could find and then destroy rail yards, bridges and major industrial targets.

These and other emerging technologies not covered by nuclear arms control agreements now in the works stand to play a large role in defending the United States in the next century after the Cold War’s arsenal of nuclear “doomsday” weapons are sharply restricted or eliminated.

Pentagon officials say that the Defense Department is pursuing plans to develop and build other powerful new conventionally armed cruise missiles, most of them using radar-eluding “stealth” technology.

All of the proposals build on the Navy’s success in deploying long-range Tomahawk cruise missiles, which were designed to carry either conventional or nuclear weapons. The Navy plans to order at least 3,630 Tomahawks, of which 2,970 would have non-nuclear warheads.

Although long-range ballistic missiles deployed on submarines would be limited by a strategic arms reduction talks (START) treaty under discussion at this week’s Bush-Gorbachev summit, the accord would not affect naval cruise missiles, including the 680 planned nuclear-tipped Tomahawks.

The new emphasis on conventional missiles is part of a broad shift toward relying more on weapons carried by ships and aircraft, which military planners consider more flexible than land-based missiles or heavily armored ground forces.

But it is also the result of years of work by the Pentagon and its contractors on developing non-nuclear weapons that could help the United States and its allies counter the numerically superior forces of the Warsaw Pact. The idea was to build weapons with sufficient range to hit massed troops, railheads and armored columns inside the Soviet Union as they stage to move toward the front lines.

Congress quickly seized on the emerging technologies--advanced sensors, propulsion and warhead designs--as a way to “raise the nuclear threshold” by allowing North Atlantic Treaty Organization armies to hold their own in Europe without the early use of nuclear weapons.

With the crumbling of the Warsaw Pact, the rationale for those weapons would appear to have dissolved. But the proposed START agreement covering long-range nuclear arms and the prospect of negotiations to reduce or eliminate short-range nuclear weapons have given new luster to programs based on emerging technologies.

Not only will the new weapons by unaffected by the nuclear arms accords but Pentagon planners also hope that their firepower will help offset the nuclear punch being traded away in superpower negotiations.

“We’re going to rely more and more on such conventional weapons,” said Dean Wilkening, a military analyst with the RAND Corp., a Santa Monica-based think tank. “As weapons of terror, these new (non-nuclear) weapons will never replace nuclear weapons. But as weapons of warfare, these high-tech conventional weapons can pick up some of the nuclear weapons’ jobs.”

But analysts warn that as the Pentagon develops and builds more of these weapons, they are certain to raise worries in Moscow and pose problems for future arms negotiations.

The Soviets, for instance, have fretted during START negotiations that systems such as the non-nuclear Tacit Rainbow could be converted to carry nuclear warheads deep into Soviet territory. Since modern nuclear warheads are smaller and lighter than conventional warheads, it would be relatively easy to fit nuclear tips on weapons designed originally to carry the heavier non-nuclear explosives.

“But the Soviet military has the broader concern that the United States is ahead in conventional precision-guided missiles and the air forces needed to carry them, and that these are excluded from limitations,” said Thomas Longstreth, an arms control analyst with the Washington-based Federation of American Scientists.

“They fear that the United States will take advantage of its technical capability in these weapons to expand these forces and circumvent the accords, and they’re trying to foreclose that option by capturing these weapons in arms negotiations,” Longstreth said.

In the START treaty, newly deployed cruise missiles with ranges above 375 miles must bear “observable differences” that would help treaty inspectors distinguish between conventionally armed and nuclear-tipped missiles.

More immediately, some analysts are concerned that use of the new conventional weapons to attack some of the Soviets’ most sensitive facilities could provoke all-out nuclear war--the exact opposite of the effect expected by Pentagon officials.

“The Soviets would look at any attack upon their homeland as cause of a total nuclear exchange,” even if it involved conventional weapons, said James Tegnelia, a Pentagon official during the Reagan Administration who oversaw the early development of many of the emerging technologies.

For now, U.S. officials defend the move toward unrestrained numbers of longer-range conventional cruise missiles as necessary for use in Third World wars. They are also critical in coping with Soviet air defenses, which defense intelligence analysts expect to become denser and more effective as the Soviets pull back inside their borders.

“Our requirement for these weapons hasn’t changed,” said one Pentagon official. “We still have to get to those targets and we can’t afford to lose people.”

THREE NON-NUCLEAR MISSILES

The Pentagon is showing new interest in conventional, or non-nuclear, missiles because of treaties limiting the superpowers’ nuclear weapons. Here are three critical types:Tomahawk:

Starting in 1984, the Navy began deploying theTomahawk cruise missile which has a range of 800 to 1,550 miles. Ther service expects to buy 3,630 Tomahawks, of which only 660 would be nuclear, at a cost of $1 million to $1.4 million each. While the Soviets are eager to negotiate limits on the weapons, U.S. resistance has left them out of arms talks for now. Length: 18 ft. 3 in.

Weight: 2,650-2,800 lbs.

Wing Span: 8 ft. 4 in.

Tacit Rainbow:

Currently under development by the Air Force, this radar-killing missile has a range of almost 500 miles and can “loiter” over targets by flying in circles. The Navy and Air Force had planned of build 18,000 of the jet-powered missiles, although that could be cut in half. The first missiles are expected to be deployed in the early 1990s with a total program cost of $4.1 billion.

Length: 8 ft. 4 in.

Weight: below 500 lbs.

Wing Span: 5 ft. 1 in.

Long-Range Conventional Stand-Off Weapon:

Still on the drawing board, this cruise missile would be used by both Air Force and Navy aircraft in the year 2000 and beyond. Its range would extend to 2,000 miles. Pentagon officials have said that 2,000 to 10,000 would be acquired at a cost of $750,000 to $1.5 million each.