The prospect of future summits between President Reagan and Soviet leader Mikhail Gorbachev has revived the idea that the United States could negotiate limits on its Strategic Defense Initiative (SDI) in return for major reductions in Soviet offensive nuclear weapons, administration sources said today.
These sources said they did not expect such a tradeoff to occur at the summit that begins here Tuesday but that the possibility now exists for a new round of talks in the future in which both superpowers would agree first to curb offensive nuclear weapons and then turn to discussions to limit both offensive weapons and missile defense.
Officials familiar with the discussion of these prospective negotiations said that Reagan may bring up this idea when he meets with Gorbachev. They cautioned that it is not known how the Soviet leader, who has made restriction of the president's missile defense plan a high priority, will react to the prospect of what could be a year's delay in putting any limits on SDI.
Rival camps within the administration agree that Soviet fears of SDI offer an opportunity for Reagan. But they are divided on how to take advantage of the Soviet concern.
The Strategic Defense Initiative, popularly called "Star Wars" and described by the president last week as "my dream," has provoked a battle between pragmatic arms controllers who would like to use missile defense as a lever for a deal and conservatives who want Reagan to resist persistent Soviet efforts to limit SDI to a laboratory research program.
In recent speeches and interviews, Reagan has given visionary descriptions of Star Wars, which he sees as a space shield that ultimately would protect civilian populations from nuclear annihilation. But in some of these same interviews, Reagan also has stressed his background as a labor negotiator for the Screen Actors Guild and pointed out that the test of a good negotiator is whether he is able to strike a bargain.
This sort of talk has worried conservatives that Reagan, despite all his proclaimed fondness for a missile defense program, might yield on its testing and development and agree to limit it in return for significant Soviet concessions on offensive weapons.
Defense Secretary Caspar W. Weinberger, in a letter to the president about arms control violations that was disclosed Friday, warned Reagan that he would be under "great pressure" at Geneva to agree to "tight limits on SDI development and testing that would discourage the Congress from making any but token appropriations."
Weinberger and his arms control specialist, Assistant Defense Secretary Richard N. Perle, have emerged as the staunchest defenders of unrestricted development of SDI. Their counterweights within the administration are national security adviser Robert C. McFarlane and, to some degree, special arms control adviser Paul H. Nitze, both of whom favor new arms control agreements entailing significant reductions of offensive weapons on both sides.
According to senior administration officials familiar with the dispute, McFarlane's hidden hope is that Reagan, despite his present enthusiasm, can be persuaded that he can strike a better bargain with the Soviets by agreeing to limit SDI than he would ever get by simply trading cuts in U.S. offensive weapons for similar reductions on the other side.
These officials say that this possibility is also the continuing fear of Weinberger and Perle and that their concern has increased as the summit approaches despite Reagan's glowing descriptions of the prospects for missile defense.
"It is true that the president has never publicly wavered on SDI," said an official who supports the program. "But it is also true that the Soviets have never given him much incentive to get rid of it. If Gorbachev offers him a deal face to face, the president would have to think about it. Given his desire to strike a bargain, who knows what he would do?"
Sources on both sides of the debate say that a new dimension to the dispute has been provided by the likelihood that Reagan and Gorbachev will agree this week to hold additional summits.
Asked whether this kept alive the idea of a trade of SDI for offensive weapons, the official replied: "Yes, I think it does."
Several officials made the point that the two sides are currently so far apart that any kind of new strategic arms limitation treaty is unlikely at this time. They also said that Reagan is too committed to SDI as a defense for the civilian population to change course overnight, even though one official expressed the view that Reagan would display "an evolving position" on the issue if he sees its value in extracting concessions from the Soviets.
A former administration official credits the idea of a trade to McFarlane, who he said viewed the SDI proposal as "the sting of the century." He meant by this description that the United States would be swapping a missile defense plan it does not have and which many scientists say would never work for existing Soviet strategic missiles with proven destructive capability.
SDI already has worked to get the Soviets to the bargaining table and the Geneva summit, this former official said. But the "sting" failed to materialize, he said, because by the time the Soviets had come forth with a substantive arms-cut proposal Reagan had become captivated by the missile defense.
Reflecting a view widely held by SDI's critics in the West, Yevgeny Velikhov, vice president of the Soviet Academy of Sciences, today termed Reagan's view of missile defense as shielding the population "a complete illusion."
Former president Richard M. Nixon also has questioned the value of missile defense as a population shield, even while saying that it is "the ultimate bargaining chip" if Reagan restricts SDI to protecting vulnerable U.S. missile sites.
But it has been difficult to persuade Reagan to limit his "dream." Ironically, officials say, this is because McFarlane, aided by the Joint Chiefs of Staff, oversold the president on the plan two years ago at a time when both Weinberger and Perle were skeptics about its utility.
Secretary of State George P. Shultz reflected this today when he was asked on ABC-TV about Reagan's view of Star Wars.
"The president is determined to find the answer to the question, 'Is it possible to construct a shield that will protect us in some measure from ballistic missiles?' . . . There is no way the president can be persuaded not to seek that answer."