At their meeting in Geneva Jan. 7 and 8, the American and Soviet foreign ministers have greater political incentives for arms control than at any time in the past five or six years. But they also face huge political and technological hurdles, and their time is short. Connoisseurs of this arcane branch of diplomacy give the superpowers only an 18-to-24-month ``window of opportunity'' in which to reach agreement. Negotiations that drag on longer than that, suggest specialists like Lawrence Freedman, professor of war studies at London's King's College, risk getting overwhelmed by the 1988 election campaign in the United States and by the sheer momentum of a destabilizing new arms race in space.
On the Soviet side the strongest incentive for arms control -- as presumed Kremlin heir apparent Mikhail Gorbachev made plain during his pre-Christmas visit to Britain -- is the desire to block an American technological leap ahead of Moscow in space, in both antimissile and antisatellite weapons.
On the Soviet side, the strongest disincentive to arms control is the transitional nature of the present leadership. This means that candidates for the top post are reluctant to expose themselves to rivals' attacks by appearing too soft and making the kind of concessions needed for a realistic negotiating position.
On the American side, the strongest incentive for arms control is probably President Reagan's apparent wish to go down in the history books as a second-term peace hero as well as a first-term hard-liner.
On the American side, the strongest disincentive is probably Mr. Reagan's reluctance to translate this sincere desire into a realistic negotiating position.
Thus, Soviet Foreign Minister Andrei Gromyko brings to Geneva Moscow's insistence so far on focusing limitations on space weapons -- where the US leads -- to the exclusion of offensive missiles. And Secretary of State George Shultz brings to Geneva Washington's insistence on focusing limitations on heavy land-based intercontinental ballistic missiles (ICBMs) -- where the Soviet Union leads -- to the exclusion of space systems.
Logically, negotiations might therefore involve a trade-off between existing Soviet offensive ICBMs and potential American antimissile and antisatellite weapons.
Yet there is little sign so far that either side is seriously interested in such an exchange.
Mr. Gorbachev did hint at this possibility in London -- but public Soviet hints on arms control often do not jibe with concrete Soviet offers, and historically Moscow has insisted on keeping offensive and defensive nuclear weapons separate.
For his part, President Reagan does agree that space weapons deployment will be subject to negotiation, according to British Prime Minister Margaret Thatcher. But as soon as Mrs. Thatcher expressed this view in Washington, Defense Secretary Caspar Weinberger and National Security Council adviser Robert McFarlane were at pains to stress that the President deems space weapons research nonnegotiable.
Theoretically, these two presidential positions are compatible, since basic research will require at least four years, and hardware testing and deployment would come only by decision of a new president. In practice, however, these are regarded by Mrs. Thatcher and Mr. Weinberger -- and by Shultz's delegation in Geneva -- as two conflicting points of view about negotiating options.
Despite all the uncertainties and remaining deadlocks, arms control advocates are at least more optimistic than they have been in five or six years. With the opening of the superpowers' first comprehensive arms control talks since the Carter administration, they hope the potential mutual benefits from arms control can now outweigh the superpowers' mutual antipathy to arms control.
In this context, arms control supporters view the new American incentives as arising from a waning of the ideological hostility to arms control of the early Reagan administration. They contend that while there are still powerful opponents of arms control within the administration, there is no longer the same concern about a nuclear ``window of vulnerability.''
Whatever remaining concern there is will be further allayed, they continue, by the forthcoming American deployment of the accurate and invulnerable Trident II submarine-launched ballistic missile and the American surge in research and development of antimissile and antisatellite weapons.
Psychologically the administration certainly believes it has turned America around, restored the country's pride, self-confidence, and governability, and started the rebuilding of American military forces. It sees the Grenada invasion and the landslide reelection of Mr. Reagan as having demonstrated American resolve and public support to the Russians. Likewise, it sees the quiet first year of NATO Euromissiles in 1984 as demonstrating NATO resolve and solidarity.
It no longer thinks there is the same need to exhort Americans, no longer the same risk of naive public lowering of its guard if real arms control negotiations proceed.
Thus, President Reagan maintains that America's standing firm over the past four years has brought the Russians back to the negotiating table with a more realistic understanding of the superpower relationship -- and of the inevitable linkage between arms control agreements and Soviet military intervention abroad.
All this means that the main internal policy arguments within the Reagan administration will probably now focus on practical and tactical rather than ideological issues.
Even without the old ideological clash over arms control as between the State and Defense departments, however, the current state of the Reagan administration is still very unclear. Tactical feuds can be just as immobilizing as ideological ones. Reagan's genial style of governance puts a premium on tolerating rather than resolving the State-Defense conflicts -- as the mixed membership of Shultz's Geneva delegation illustrates. And in such a complex issue, any deadlock the President does not resolve automatically favors inertia and therefore the opponents of arms control.
Much less is known, of course, about internal Soviet debates about the new round of nuclear arms control. Clearly Moscow is alarmed about the potential of an American surge in space and would like to block it by arms control without requiring any Soviet concessions. The Kremlin may also have learned something from its fumbling of the Euromissile arms control negotiations last year, when it took a hard line and gambled that European public opinion would make new NATO deploy-ments impossible. Instead, the adamant Soviet position swung European public opinion behind the stationing.
Further Soviet incentives to explore serious negotiations in Geneva this year could arise from the realization that Moscow has only that short 18 to 24 months in which to get agreed limits on American space programs or else see American election-year politics devour any budding agreement. Finally -- well down on the list of Soviet priorities as a still controversial point in the Kremlin -- the Moscow leadership would probably welcome a pause in spiraling weapons costs in order to pursue reforms in the sluggish Soviet economy.
For both sides, then, new incentives for arms control are in evidence. Arms control requires military concessions, however -- i.e., subordination of lower to higher military and security priorities.
On the Soviet side, these are extremely hard to make for a nation that is a conservative military superpower but feels itself inferior to the US economically and diplomatically. Historically such concessions have come from Moscow only after a single leader has so consolidated his power that he is no longer vulnerable domestically.
On the American side, such concessions are extremely hard to make for a can-do superpower that tends to trust its own technological exuberance rather than the messy compromises of diplomacy.