When US and USSR both change at the top

It is now likely that for only the second time since World War II a major leadership change in the Soviet Union could coincide with a similar change in the United States. Already prominent political analysts are suggesting Ronald Reagan is unlikely to be a two-term president for two reasons: He is already over 70 and may be unwilling to undergo again the rigors of a presidential campaign. In addition, even though his economic program is unusally controversial and may be a unique electoral handicap in 1984, it may also be true that any program to restructure the American economy is likely to raise the social level of pain to a point that incumbents will suffer at the polls.

Within the Soviet Union there are also growing signs of a leadership change. The press treatment of Leonid Brezhnev increasingly seems designed to prepare the Soviet people for change. During Brezhnev's recent trip to Bonn, for example , Pravda ran a front-page picture of Brezhnev that could not fail to suggest to ordinary Soviet readers that their nation's top leader is in ill health and must soon pass from the political scene.

The first time a major leadership change took place in both the superpowers was in 1953. It was the year of Eisenhower's inauguration and Stalin's death. The issue then as it will be soon is how the West should react to such a sudden change at the center of the world's diplomatic stage.

One view held in 1953 was that of Winston Churchill, who believed that such a fundamental turning point in Soviet history could create a unique opportunity for the West. He therefore urged Eisenhower to agree to an early summit meeting with the new Soviet leadership under Georgi Malenkov, who within a few brief months advanced twin heresies. He raised the priority given to the consumer in Soviet society and he stated that nuclear war would ''probably'' mean the end of civilization. (It took the Soviet Union until the end of the Brezhnev period of 25-plus years to recognize the wisdom of these twin heresies.)

Under Malenkov, the Soviets undertook a number of accommodating decisions: They accepted Dag Hammarskjold as UN Secretary General; they urged more rapid progress in the Korean War negotiations, which succeeded a few months later; they negotiated the Austrian peace treaty; they renounced territorial claims on Turkey; and they established diplomatic relations with Greece, Israel, and Yugoslavia.

But they also maintained their cruel grip on Eastern Europe and continued to be caught in a paranoid view of the world. Secretary of State Dulles persuaded Eisenhower to resist Churchill's advice, and the summit meeting was delayed until 1955. By that time the more accommodative Malenkov had fallen from power. Replacing him were men determined to preserve the traditional priority accorded heavy industry and Soviet defense.

The second leadership change occurred with John F. Kennedy's assassination and Nikita Khrushchev's fall. That change was less traumatic since the code word for successors in both countries was continuity and stability.

The leadership change now in prospect seems more likely to resemble that of 1953 than that of 1963-64. Of course, historical parallels are never exact. The men who replace Brezhnev are unlikely to resemble Malenkov and no one on the American scene resembles Eisenhower. But there are similarities.

Each country is in the opening stages of a new arms race that as in the past will raise fear more than security. As then the international scene is also entering into an unusally dangerous period of superpower tension. Finally, as in the early '50s, both Eastern Europe and the third world are explosive.

In the current circumstances does a Churchillian effort to reach out to communicate make sense? The answer is yes if one understands that the goal of summit contact then and now cannot be the same.

In most of the postwar period the main goal of summits was to break bottlenecks that lower ranking officials could not crack. But the level of understanding is now so low, and the respective stakes are now so high, that no breakthrough at any level is likely. A summit meeting based on the expectation of a breakthrough would simply fail. The purpose of summits now is not to seize major historical opportunities as in 1953 but to chip away at progressively dangerous and otherwise rising levels of suspicion.

For that to happen, however, not one summit is needed but regular summits. Regularity could preserve the educational advantages of encounters at the highest levels yet could lower public expectations of a policy breakthrough developing from any single meeting.

A few years ago the Soviet Union advanced a proposal for a single meeting of the UN Security Council at the head-of-government level. Perhaps a better approach would be an understanding that the top leaders of the two superpowers would accept the responsibility that once a year each would address the UN General Assembly or the Security Council with a state-of-the-world message. Then - as now happens without too much fanfare for the Soviet foreign minister and the US secretary of state - the two heads of government could meet informally without excessive expectations but over time with valuable effect.

Nearly 30 years ago with Stalin's death Western determination to keep the diplomatic doors closed lost the West an historic opportunity. This time around, with Brezhnev's departure and yet another change in the US likely, let us try to be sure that diplomatic doors remain open.