Who rules is far less important in the Soviet Union than in the United States. Russia's enduring problems far outweigh the personalities who rise to the top of the party hierarchy to deal with them. The resources available to Soviet leaders are far more constrained than those available to the White House. And while Americans demand change, many Soviet citizens prefer stability.
Differences among Soviet leaders since the Stalin years have been more of style than of substance. Khrushchev zigged and zagged without always consulting his colleagues. But after he fell, his policies persisted. As China charged, Brezhnev's rule amounted to ''Khrushchevism without Khrushchev.'' Despite Andropov's emphasis on work discipline, his brief 15 months could be called ''Brezhnevism without Brezhnev.''
Konstantin Chernenko inherits the same dilemmas that have confronted Soviet leaders for decades. How to ease the burden of arms racing and reduce the danger of war without accepting a military balance that favors the West? How to unleash the creative and work energies of the Soviet people without opening the floodgates to excessive ''spontaneity'' - not just in the USSR but in Eastern Europe? How to integrate more meaningfully in the world economy without renouncing all claim to a unique and superior form of social organization? How to enjoy the potential gains without suffering the likely losses from taking part in a network of global interdependence?
Soviet leaders have affirmed that humanity faces interrelated global problems so complex that they cannot be resolved by any one state, no matter how powerful. For nearly three decades the dominant Soviet response has been to pursue arms control and trade with the West while eschewing programs to help the third world. In effect, Moscow has affirmed the value of East-West interdependence while viewing the third world as a zone for confrontation. A second school has dismissed the prospects of meaningful cooperation with Washington and instead urged a Soviet strategy to penetrate the emerging nations. A third school, less prominent, urges a return to Fortress Russia, the safeguarding of her resources and the purification of her life style. A fourth school urges not only East-West but also North-South collaboration to deal with the problems of global interdependence.
Soviet policy has been eclectic, choosing from each approach in response to an evolving mix of challenges and opportunities. In the early 1970s, Brezhnev linked his name to a party ''Peace Program'' endorsing detente and trade. Had his emphasis borne fruit it might have spilled over into North-South relations as well. By the mid-1970s, however, US-Soviet trade had expanded very little. The Kremlin then became more militant in the third world, from Angola to Afghanistan. Washington, in turn, moved from arms control to arms racing.
Just as the Soviet economy depends mainly on the weather (decisive for agriculture), so Moscow's foreign policy hinges mainly on the US. The carrots and sticks the Kremlin perceives in American behavior are probably the weightiest factors moving the Soviets as they consider one approach or the other to their external dilemmas. Soviet actions and words, of course, also affect US decisions on foreign policy.
A change of emphasis in both capitals could help the superpowers move back from the precipice of confrontation in the third world and in military competition; back toward detente and exchanges of goods, science, and art; and on to the steps needed to deal with problems so complex that no nation can deal with them in isolation.