Kremlin leaders never fight an election campaign at home with such vigor and persistence as they are now doing indirectly in West Germany.

The immediate Soviet objective is obvious. If the Social Democratic challenger Hans-Jochen Vogel emerges victorious in the March 6 balloting, the planned deployment of new American medium-range nuclear missiles in West Germany may be abandoned.

But what is perhaps not so obvious is Moscow's long-term objective in West Germany as revealed in recent diplomacy between the countries.

The almost exclusive public focus on the missile question during the recent visit to West Germany by Soviet Foreign Minister Andrei Gromyko has been somewhat misleading.

The extraordinary thing about the visit was that Gromyko could be in West Germany in the middle of an election campaign without arousing controversy and that the visit itself came at the initiative of the incumbent Christian Democratic government of Chancellor Helmut Kohl.

From Moscow's point of view, this reflected a qualitative change in West Germany. The essence of the Soviet effort to exploit this change was revealed by Gromyko during his Jan. 18 press conference in Bonn.

"We would like the Federal Republic of Germany," Gromyko said, "when building its relations with the Soviet Union to display its own self, to be guided by its own interests and not to yield to foreign influence if they do not meet these interests, the interests of maintaining good relations with the Soviet Union."

Gromyko's reference to Germany's "self" is without precedent and is particularly significant considering Moscow's fear of German nationalism since Hitler's invasion of the Soviet Union during World War II.

What Gromyko sought to convey is Moscow's awareness of the emotional stirrings beneath the surface of West German public life that are reflected in the emergence of an antinuclear movement and the environmentalist party known as the Greens.

There are at least three reasons leading the Soviets toward encouraging what Gromyko delicately called Germany's "self."

One is that Moscow sees this nationalism as adopting an anti-American sentiment. Nobody here expects a significant weakening of West German-American ties, but under the Reagan administration there has been a perceptible change in these relations. One example is that while president John F. Kennedy was able to ban West German exports of large-diameter pipes to the Soviet Union, Reagan was not able to impose a similar ban on the Siberian gas pipeline project.

The second reason deals with France, which under President Francois Mitterrand has emerged as the strongest supporter of Washington on the question of deployment of new U.S. missiles in Western Europe. In the past, Bonn was able to resist certain U.S. policies by finding allies in Paris.

The third and perhaps main reason is the German national question. Any Bonn government has to maintain ties with Moscow because this is the only way for West Germany to maintain links with East Germany. Even if the dream of a reunited Germany is not realistic at this stage, the links between the two Germanys are psychologically and emotionally important.

Mitterrand's cooling of relations with the Soviet Union, which were better under his predecessor Valery Giscard d'Estaing, constitutes perhaps the most significant setback for Moscow in recent months in Europe. As long as the French were backing West German positions, Bonn was seen here as having increased leverage with Washington. With the French now reverting toward strategic cooperation with the United States, the Russians see their European policy as being seriously jeopardized.

In this context, West Germany is seen here as more isolated and more vulnerable than before.

The Russians believe that irrespective of the outcome of the German elections, no West German leader should be expected to sanction the deployment of 108 Pershing II nuclear missiles in West Germany.

Given the concern here about these weapons, which can reach the Soviet Union in eight minutes, the Russians are expected to go to any length to prevent their deployment. Moscow has substantial political, economic and institutional resources to create major social turmoil within West Germany, and the Russians believe that this is understood by all political figures in Bonn.

Although the Russians would welcome a Social Democratic victory, it is worth noting that they have kept their contacts with Kohl's government open, seemingly in an effort to have both sides clearly understand the nature and extent of Soviet concerns.

The post-Brezhnev phase of Moscow-Bonn diplomacy came shortly after Leonid Brezhnev's funeral when his successor, Yuri Andropov, met with West German President Karl Carstens and Foreign Minister Hans-Dietrich Genscher. The West Germans raised the question of Gromyko's visit to Bonn, presumably because the Kohl government wanted to demonstrate that it was capable of continuing a dialogue with Moscow and thus acquire some political capital.

Andropov immediately agreed, apparently to show his interest in continuing close contacts with the conservative government despite its pro-American tendencies. But the Soviets promptly and discreetly arranged for Vogel's visit here, and they treated him as a head of government.

Not only did Andropov meet Vogel for two hours--more than any foreign leader thus far--but they also had a separate conversation with only an interpreter present. Vogel also met with Premier Nikolai Tikhonov to discuss economic issues and was briefed on the questions of arms control by the top military and diplomatic officials involved.

Given the standard nature of Moscow conversations, this one seemed to have reached a new level in openness and mutual understanding.

Once Vogel's visit was over, Gromyko went to Bonn. His task was to give a detailed account to Kohl of Moscow's position and impress upon him that Bonn in the future cannot ignore Soviet concerns particularly on an issue such as the Pershing II deployment.

The same point was revealed indirectly but forcefully during Gromyko's press conference in Bonn.

"I shall to some extent divulge a secret," Gromyko said, "but I hope that there will be no rebuke on the part of Chancellor Kohl. At the end of the conversation I asked him directly whether I could, upon my return to Moscow, tell the Soviet leadership as a whole and General Secretary Yuri Andropov personally that the leadership of the Federal Republic of Germany favors detente, the course which positively manifested itself during a whole number of years in the relations between our two countries, and that this course will remain in force. The chancellor answered in the affirmative to that question."