President Reagan's recent "program for peace" speech and Soviet President Leonid Brezhnev's visit to Bonn this week have dramatized a psychological battle for European public opinion that promises to be very much a part of U.S. and Soviet tactics surrounding the arms-reduction talks that begin Monday in Geneva.

What makes the new U.S.-Soviet talks different from the low-profile strategic-arms negotiations of years past is Western Europe's extraordinary interest and indirect role in the process -- a fact that each superpower is now trying to turn to its own advantage.

For the United States, the fact that its medium-range nuclear missiles on the bargaining table in Geneva are planned for deployment in Europe has made necessary a campaign for continued European support of its position.

But the Reagan administration, adjusting to office this year and believing deeply in its own rearmament mission, was slow to compromise with West European demands. The Soviet Union thus gained the propaganda advantage early without much trouble. Lately, Washington seems to have caught up.

The Europeans have not been a passive audience in the drama. West German Chancellor Helmut Schmidt has fashioned for himself a role as what he calls "interpreter" between the main East-West players.

"We are the ones mainly concerned" about the negotiations, declared Bonn spokesman Kurt Becker this week. "Either as the target of Soviet rockets or the place where the U.S. deployment will take place."

Schmidt's agreement with Brezhnev on West German-Soviet consultations that will parallel the U.S.-Soviet talks in Geneva would appear to add a new diplomatic dimension to nuclear weapons negotiations which up to now were strictly a bilateral affair.

The Bonn leader is accountable to his Social Democratic Party and the West German electorate, where there is substantial opposition to plans -- agreed upon unanimously by NATO governments -- to deploy U.S. Pershing II and cruise missiles in Western Europe. This gives added significance to American and Soviet attempts to sway Western Europe, particularly West Germany.

"There have never been any negotiations so much in the public limelight as those starting now," said Karl Kaiser, director of the German Society for Foreign Policy, in a recent interview. "Every move will be a matter of domestic politics, at least on this side of the Atlantic."

In targeting European opinion, the United States and the Soviet Union have drawn on an arsenal of verbal weapons, including official speeches, visitor exchanges, interviews in the West European media and issuance of special publications, all intended to stress the nuclear threat to Europe posed by one or the other superpower, depending on which side is talking.

Additionally, the Soviets are believed to have used Western Communist parties and various other groups that they control to help organize a number of demonstrations against the planned U.S. missile deployment.

America's intention in the debate is to keep the message simple by focusing on Soviet land-based, medium-range rockets, for which the United States has no equivalent deterrent in Europe.

Moscow's interest is in complicating the issue by pointing to a broad range of other U.S. nuclear forces in Europe and demanding that they be included in negotiations. This approach tends to run U.S. and Soviet weapons systems and nuclear-force ratios into a confused muddle, which suits the Soviet aim of drawing attention from the single category of land-based systems.

Throughout the year, Moscow has conducted campaigns of one sort or another on the peace issue -- against the neutron weapon, against the concept of limited nuclear war, in favor of nuclear-free zones. All have found some resonance in Western Europe, especially against the background of bellicose American pronouncements.

The Soviets have sought to portray themselves as part of Europe and thus genuinely concerned for the fate of the continent in a way the Americans, located an ocean away, are said not to be. The Soviet arms development -- replacing single-warhead SS4 and SS5 rockets with triple-warhead, more accurate SS20s -- is described by Moscow officials as routine modernization that will not alter what the Soviets say is a rough balance of East-West nuclear forces in Europe. In contrast, the Soviets argue, the new U.S. missiles would seriously change the strategic balance.

U.S. officials say in response that the Pershing II and cruise missiles are necessary to offset the SS20 threat and more firmly link Western Europe to America's nuclear deterrent.

At stake, though, is far more than maintaining West European public support for the new U.S. missile deployment. Both the Soviets and the Americans are reaching for a psychological wrench that will either loosen or tighten the bolts of the Western Alliance.

"The Soviet Union is conducting a vast orchestra of propaganda," said Eugene Rostow, chief of the U.S. Arms Control and Disarmament Agency, in a speech last month in Bonn, "trying to convert the reasonable concern about nuclear weapons of troubled people throughout the world into a tidal wave of opinion that would stop Western rearmament, split the United States from its allies and bring Western Europe, Japan, China and many other countries and regions into the Soviet camp."

Rostow's remarks were a warning to Western Europe to be on guard. But they also reflected the Reagan administration's belated realization by the autumn that it had to start an informational campaign of its own to counter the Soviet drive.

Initially the administration, while well aware that the pro-detente mood in Europe was out of step with an anti-Soviet pro-rearmament mood in America that helped to elect Reagan, assumed the West Europeans could eventually be brought around by lots of pep talk.

Assistant Secretary of Defense Richard N. Perle, in Bonn in April with his boss Caspar W. Weinberger for a meeting of Western defense ministers, told reporters, "There is a new spirit in the United States with which we hope to infuse Europe." The plan called for Western leadership by U.S. example.

But the West Europeans were not following, and the Soviets saw it early. Reagan's harsh anti-Soviet rhetoric, his administration's tough posturing over El Salvador, its big defense budget and lack of interest in early arms-control negotiations, all unsettled Western Europe.

In response, the Soviets launched a peace initiative at their 26th Communist Party congress in late February, when Brezhnev suggested a summit meeting with the new U.S. president in an effort to restore "normal relations." Brezhnev's speech also contained calls for renewed arms-control efforts, including a proposal for a freeze on deployment of more SS20 rockets targeted on Western Europe, providing the Americans would cancel their own deployment plans.

To promote the Soviet program, Moscow dispatched several of its most articulate spokesmen, including Soviet information chief Leonid Zamyatin and Moscow Institute leader Georgi Arbatov, to key West European cities for public appearances.

Schmidt and other West European officials, meanwhile, urged the Reagan administration to return to the negotiating table with the Soviets as soon as possible. The one lever the West Europeans had in this regard -- and they leaned hard on it -- was the 1979 Atlantic Alliance decision which had committed Washington to seeking arms-limitation talks with the Soviets in return for European support of the U.S. missile deployment.

In May at an alliance ministerial meeting in Rome, Secretary of State Alexander M. Haig Jr. disclosed to his European colleagues a plan for engaging the Soviets in talks: first through high-level diplomatic contacts that, by the end of 1981, would lead to the opening of formal negotiations.

But West Europeans continued to doubt Washington's serious interest in negotiating. In July, at the summit meeting of Western leaders in Ottawa, Schmidt received a letter from Reagan stating the president's commitment to the talks and meant, when its contents were leaked in Bonn, to put Europe's doubts to rest.

Whatever positive effect that letter might have had was washed away in August with the news that Reagan had decided to produce and stockpile the neutron weapon, the mention of which sends chills down the spines of Western Europeans. The stockpile was to be in the United States, but the Soviets had a field day.

The neutron-weapon decision, followed in October by Washington's fumbled attempt at explaining the Western strategy of controlled nuclear responses, fueled a series of protest marches throughout Western Europe.

Its slip-ups aside, the Reagan administration has appeared to be making a concerted, if belated, drive for European public support that reached a high point with Reagan's speech.

The campaign seemed to start in September with Haig's visit to West Germany, during which he voiced understanding of the feelings of the anti-nuclear protesters, thousands of whom demonstrated against him in West Berlin.

At that time, the secretary of state also showed the first sign of official U.S. softening toward the "zero option" proposal for the Geneva negotiations that Reagan has now embraced. Under the proposal, the United States has offered to cancel its planned missile deployment if the Soviets dismantle their SS20, SS4 and SS5 missiles.

Haig at first dismissed the idea as "ludicrous" in a German TV interview. But after conferring with Schmidt, whose party associates were pushing for the scheme, Haig conceded publicly that it might be worthy of consideration "under ideal conditions." A month later, at a meeting of Western defense ministers in Scotland, Weinberger agreed at West German and Dutch urging to have the idea recognized in an official alliance communique as "a possible option."

There are signs the Soviets, who started out the year with the propaganda advantage in Europe, may be feeling themselves on the defensive. The surfacing of a Soviet submarine in Sweden this month, and the discovery that it was evidently carrying nuclear weapons, was a definite setback.

In Geneva, they are under the gun. Previous strategic-arms negotiations had no specific time frame. But if no agreement is reached in the new talks by late summer 1983, Schmidt told Brezhnev that West Germany and the other Western alliance members would proceed with deployment of the new missiles.

The Soviet moratorium proposal is a way of trying to stop the clock for the American deployment. Mixed in, too, among Brezhnev's peace gestures last week were veiled threats of consequences and countermeasures if the deployment takes place.

According to his spokesman Zamyatin, for instance, Brezhnev said that Soviet missiles, now pointed only at military targets in Western Europe, might be redirected at civilian centers.

But such talk does not necessarily serve the Soviet cause. "We think they are in trouble, getting caught between their propaganda and their diplomacy," said a West German source who was close to the German-Soviet discussions. "It will be hard for them to maintain that they are not threatening Europe, that they are ready for arms cuts and withdrawals, while adding that if the negotiations don't produce an agreeable result, they will pound the holy daylights out of Europe."