The US negotiating team arrived in Geneva this weekend armed with 12 pages of instructions and a mandate from President Reagan to ``explore every promising avenue for progress'' in long-awaited arms talks with the Soviet Union, scheduled to begin on Tuesday. ``I have to say I have never seen instructions that provided any negotiators greater latitude for serious give and take,'' said national-security adviser Robert C. McFarlane in describing to reporters on Friday the President's last-minute instructions to lead negotiators Max M. Kampelman, former Sen. John G. Tower, and Maynard W. Glitman.
Sources here say the United States has two basic objectives: to get the Soviets to agree to deep cuts in long- and medium-range offensive weapons, and to preserve its options on research and possible future testing and deployment of space-based defenses.
But despite greater flexibility regarding offensive nuclear weapons, many here feel two factors may make a breakthrough in Geneva difficult, if not impossible: the administration's determination to make good on plans to develop space-based ballistic missile defenses, and its determination to press the Soviet Union on alleged cheating on earlier arms control pacts.
The US and Soviet delegations have arrived in Geneva at a time when both sides have renewed interest in reaching an agreement.
After keeping the Soviets at arms length during his first term, Mr. Reagan now says there is ``no more important goal'' than achieving progress in the new round of arms control discussions. Concerned about the US commitment to space-based defenses and with an economy sagging under the burden of heavy defense spending, the Soviets are also known to welcome some acceptable form of reductions.
``Both sides realize that wide-open, completely unconstrained arms competition would have destabilizing effects, plus great costs,'' says Raymond Garthoff, an arms control specialist at the Brookings Institution in Washington, D.C. ``Therefore, there's some real interest in trying to find solutions.''
But translating hopes into accomplishment won't be easy, say Mr. Garthoff and others. In particular, experts ask whether it will be possible for the administration to marry traditional arms negotiations with plans for the new system of missile defenses that the President hopes to make the cornerstone of future US nuclear policy.
Here is how arms control specialists assess the prospects for the talks:
Strategic weapons. Progress may come most easily here. The United States and the Soviet Union have rough equivalence overall in strategic weapons. The US holds the advantage in bombers and air-launched cruise missiles; the Soviets maintain superiority in heavy ballistic missiles. According to Mr. McFarlane, the administration will seek ``trade-offs between our areas of advantage and theirs,'' leading to substantial overall reductions as the basis of the US negotiating position. McFarlane notes that the President has established overall goals for reduction and has given US negotiators plenty of running room to reach lower ceilings.
Medium-range weapons. When talks broke down in Geneva last year, the US and the Soviets were far apart on how to reduce intermediate-range nuclear forces (INF). Administration spokesmen say the US goal at the new talks will be to exchange reductions in current and planned INF deployments for cuts in the Soviet arsenal of medium-range, three-warhead SS-20 missiles.
The Soviets have so far refused to agree even in principle to deployment of any US missiles in Europe. They have also demanded enough forces to offset independent British and French nuclear systems. As the talks begin, the question remains ``whether the Russians will grant to the US the right to match their [nuclear] military power in Europe or whether the US will grant superiority in Europe to the Soviets,'' says Barry Blechman, a senior fellow at the Georgetown Center for Strategic and International Studies in Washington, D.C. Many here are concerned about an impasse on the issue and speculate that the Soviets may hold any agreement on reductions in strategic weapons hostage to US concessions on INF.
Defensive weapons. Here, the Soviets could hold any agreements in both categories of offensive weapons hostage to concessions on defensive weapons.
Two years ago, the administration announced plans for a Strategic Defense Initiative, a massive research effort to develop a new type of space-based, non-nuclear defense against nuclear attack. The administration says that its SDI program can be a subject for discussion, but not for negotiation at Geneva.
The Soviets argue that what the US describes as a defensive system confers significant offensive capabilities on the US and warn that without concessions on SDI, they will compensate with a major buildup of offensive weapons.
Critics in the US say the debate over SDI has introduced a new and perhaps intractable element into the Geneva talks. They argue that the US cannot ask the Soviets to accept SDI and deep cuts in offensive weapons at the same time, without undercutting the credibility of the US negotiating position.
``Something has to give,'' says one arms control expert. ``Either the US has to agree to a moratorium on testing and deployment of defensive systems as a bargaining tool for reductions in Soviet offenses or to more generous concessions on offensive weapons as the price of unfettered development of SDI. We can't have it both ways.''
But in a meeting with reporters last week, Richard R. Burt, assistant secretary of state for European affairs, made clear the administration's position that any limits on SDI woud be ``premature.'' Mr. Burt noted that the Soviets are well along in developing their own defense capabilities. ``All we're asking for is what they've got,'' he said.
The other key sticking point in the negotiations will be the question of compliance, experts say. In two reports issued in 1984, the administration alleged Soviet cheating on previous arms control agreements. Administration officials now hint that compliance may be a precondition to progress in the current talks.
``It's difficult to make progress without clearing up the serious issue of Soviet compliance,'' Burt said. ``This is not a threat to the Soviets, but a fact of life.''
Critics say the administration's position amounts to burdening the Geneva arms control talks with issues that could be and should be resolved by the Standing Consultative Commission. This group, which also meets in Geneva, was set up in 1972 specifically to deal with compliance issues.
``If the administration goes in with this kind of emphasis on compliance, they'll have to come back with an agreement that dots every `i' and crosses every `t', '' says Barry Posen, an arms control specialist at Princeton University. ``Under the circumstances, there will be no room for ambiguity. That means asking the Soviets for concessions they'll never make.''
Mr. Posen says that if compliance issues have to be raised at all, they should be postponed until an overall agreement has been reached. Progress in the talks now reduces to how much give there will be in each side's negotiating position.
``We're prepared to be flexible,'' says Burt.
Just how flexible will be the key.
``The Soviets will clearly hang tough on the questions of linking offensive and defensive weapons,'' says Raymond Garthoff. ``If the administration insists on keep SDI open, it's bound to make it more difficult to reach an agreement.'' -- 30 --