Pressure is growing from sectors of the administration and the U.S. military to consider applying some "Star Wars" technology to more near-term limited use rather than waiting for the results of President Reagan's longer-term antimissile defense research project, according to visiting U.S. government officials.
These officials say such pressure is being resisted by the White House, but they note that technical progress in some areas of research is proceeding faster than many people realize. They acknowledge that some portions of the missile defense technology, if it works, will be available sooner than others and could be useful in limited roles.
The main role, they say, would be in a land-based defense of some existing U.S. Minuteman ICBM bases or future silos for the new MX missile. Under the 1972 U.S.-Soviet ABM treaty, the United States is allowed to deploy 100 interceptors around a missile base.
They also mention schemes to defend command centers and submarine ports, and a possible mini-defense in Western Europe against shorter-range Soviet tactical missiles that threaten allied ports and airfields.
But two key U.S. officials said that despite the pressure to move ahead in these areas, administration policy is not to make early commitments on pursuing such specific developments. This is because research is moving so fast that they do not want to risk selecting the wrong technology nor fail to explore all the technologies that are part of what is formally called Reagan's Strategic Defense Initiative.
The officials said that it was better and less expensive to make mistakes in a prolonged research phase than in a specific weapons-development effort. One official cited the Army's deployment of a big and expensive TacFire field computer system, much of whose mission now reportedly can be carried out by hand-held computers, as an example of a technical decision made too soon.
The officials also said that public discussion of the missile defense plan focuses too much on the idea that the shield over the United States that one day might make nuclear weapons obsolete, as President Reagan suggested in announcing it, would be based in space.
They said that while space may play a part in any system that evolves, such a system also could rely on ground-based interceptor missiles and computers and airplanes carrying sensors to detect approaching enemy missiles.
One official said that progress is moving fastest in new motors for ground-based interceptor missiles that enable them to zoom out to intercept a target, in super-computers meant to calculate instantly which incoming missile warheads are real and which are decoys and in long-wave, infrared detection and sorting schemes.
The defense plan envisions a so-called layered defense in which enemy missiles might be knocked down at any point from seconds after they are launched through their final dive toward their targets. But one official said most progress now is being made on possible interception in what is called the high endo-atmosphere, meaning at the fringes of but still within the earth's atmosphere, as the missile warhead descends toward earth. He said progress is also being made on interception in the exo-atmosphere, which is in space but not at the farthest distances. This also could be done by ground-based systems.
It is the ability to shoot down a Soviet missile immediately after it takes off that almost certainly would require most space-based components and weaponry so that, in effect, it could look down on Soviet bases and fire. This would have the advantage of knocking out missiles before they can disperse the 6 to 10 nuclear warheads each carries.
But other officials suggest there is growing awareness of how tough this would be, for example requiring laser beams from space to penetrate the atmosphere, which can distort them. And they talk of Soviet countermeasures, such as faster-accelerating ICBMs, and of the fact that boost-phase interception would mean a U.S. president would have to make a decision to fire his space-defense weapons within seconds of detecting an enemy missile launch.
Administration officials also have begun to temper the impression left by the Reagan program at its outset that some perfect defense is possible.
In a press conference here last week, Defense Secretary Caspar W. Weinberger talked of a "thoroughly reliable" defense. In a speech here today, Kenneth L. Adelman, director of the U.S. Arms Control and Disarmament Agency, talked of even a "less than perfect defense" reducing the risk of nuclear war because it raises uncertainty for any attacker. Former senator John Tower, newly nominated to head the delegation at revived strategic arms talks with Moscow, made similar remarks at a press conference Friday.
These officials, their aides and others from the administration, have been traveling through western Europe in recent days in what appears to be a campaign to convince skeptical allies of the merits of Reagan's plan.
Weinberger said here that the missile defense research is controversial because it challenges conventional thinking. But in private sessions here, he, Adelman, and others continued to encounter severe doubts from British specialists about where such a program could lead.
Even one of the U.S. visitors told a reporter privately that support for Star Wars had become like a loyalty oath within the administration and that he was concerned that there was not enough discussion of what the project could do for stability between the two superpowers.
Weinberger was told privately by leading academicians that he was peddling a dangerous illusion, as one put it, and toying with the sensitivities of the public by suggesting that some real defense against a determined nuclear attack is possible. The speakers said Reagan's Star Wars plan is in the same mold as proposals to disarm unilaterally to guarantee peace.
Although Weinberger publicly sought to reassure allies that there was no cause for fears of separating the United States from Europe "or anything of that kind" because of the defense work, he was told privately that there was no way to shut off what many specialists saw as growing and increasingly tough questions about Reagan's plan.
The point was made that the plan already has raised many political issues but that it will be many years before there are any technical answers about whether Star Wars will work.
A U.S. lawmaker at the private talks here said arms control negotiations would force American answers before they were available and wondered whether the Strategic Defense Initiative, if it doesn't work, would wind up destroying the current balance of power should an offensive missile race get underway while it was being researched.
A non-government participant in the private conferences on the subject asked whether Star Wars, so controversial and so personally identified with Reagan, could survive under another administration, and whether designers of offensive weapons and countermeasures could outpace those working on defense in the next 10 years.
The defense plan originally was described as taking perhaps until the turn of the century to explore fully. Even those talking about near-term use of limited defenses also are describing systems that for the most part would not be in place until the 1990s.
Weinberger, Adelman and others have all stressed publicly that mutual deterrence based on offensive systems will continue to be necessary for many years, though, they hope, at lower levels.
"This period could last 10 or 15 years or longer or even indefinitely, depending largely on the progress and results of the ongoing SDI research," Adelman told the International Institute for Strategic Studies today. This, he said, could be followed by a transition phase to more reliance on defense, "one involving the Soviets and the allies intimately all along the way."
There was also a hint of skepticism about Star Wars voiced here last week in a speech at Cambridge University by NATO Secretary General Lord Carrington, the former British foreign minister.
While supporting the need for U.S. research to keep up with extensive Soviet efforts, Carrington asked, "Could we devise and deploy a system which would increase the security of the United States and its allies?" He said he had heard arguments of both sides and was "not convinced the case has been made out either way."
He also said, "It will, at the very least, be extremely difficult to devise a system of strategic defense which meets these objectives of balance, no superiority and enhanced deterrence."
He was referring, he said, to the agreement hammered out with Reagan by British Prime Minister Margaret Thatcher in December, which many allied governments are counting on to cause the United States to negotiate about such defenses before going beyond the research stage.