Soviet President Leonid I. Brezhnev's passing could mean significant change over the long run, leading to greater competition - or greater cooperation - between the US and Soviet superpowers.
In Washington's view it could go either way.
The Reagan administration is reacting calmly to this momentous event. Administration officials have long expected it to occur and have had a great deal of time to ponder its implications.
In the end, administration analysts say they decided they could exert little influence on the struggle for succession in the Kremlin. US officials say that for the immediate future, the new Soviet leaders won't confront Washington with any dramatically aggressive foreign policy moves.
Some administration officials, including CIA director William J. Casey, say they expect a more sophisticated Soviet foreign policy to emerge over time, possibly including a move to defuse the Afghanistan crisis.
But the Soviet Union is viewed here as a militarily powerful adversary that will continue to steadily pursue the goal of expanding its influence worldwide. Analysts say they expect the Soviets to place their highest priority on cooperation with Western Europe and on encouraging the antinuclear movement there.
The Soviet Union is also viewed, particularly by analysts in the White House, as a power in the midst of an acute economic crisis and burdened by costly overseas commitments. President Reagan and his aides apparently hope to convince the new Soviet leaders that they can't improve their economy without moderating their country's international behavior and reducing those commitments.
US officials predict that after a transition period of collective leadership in the Kremlin, Yuri Andropov, the suave former KGB chief and now a Central Committee secretary, will emerge the winner in the struggle for succession.
Another favorite of Kremlinologists for the top position in Moscow is Konstantin Chernenko, another party secretary and former Brezhnev aide and protege. He is viewed as something of a paper shuffler compared with the handsome, worldly, well-tailored, and silver haired Andropov. Mr. Andropov, the son of a railroad worker, went on to a career of policing dissidents and directing the suppression of the 1956 Hungarian uprising. By all accounts available to Americans, Andropov is one of the most intelligent of the Soviet leaders.
There are several reasons why the Reagan administration is reacting calmly and deliberately to the historic change in the leadership of its huge, complicated, and militarily powerful chief adversary:
1. US officials say they expect a continued, cautious approach to world affairs from Moscow until the new Soviet leaders can further sort out their standing among themselves. The Soviets showed considerable caution during the recent crisis in Lebanon. Some analysts say that the Soviets are now over-extended, given their commitment to beleaguered friends in Afghanistan, Poland, Ethiopia, and Angola, as well as the economic and military supply burdens they've incurred in Vietnam and Cuba.
2. US Secretary of State George P. Shultz and other officials say they believe that the US and its NATO allies must confront the Soviets from a position of greater strength and unity, and that this is being achieved. Through recent negotiation, the Americans and most West European nations have moved in the direction of greater unity by essentially resolving the conflict over US sanctions against European companies that are helping to build the Soviet-European natural gas pipeline. In the White House view, the virtually completed agreement on this issue marks an important first step toward limiting the concession credits and sensitive Western technology that have gone to the Soviets in the past.
3. Secretary Shultz apparently has decided that playing ''Kremlin politics'' is a hopeless game. What is most important, in Shultz's view, is not to play a guessing game over how one can encourage the emergence of a preferred leader or policy in the Kremlin. Instead, the US must make sure that whoever emerges at the top does not misunderstand the Reagan administration and has a clear picture of how that administration views the world. US Kremlinologists have learned from being almost consistently wrong in the past to be wary about predicting leadership changes in a closed society like the Soviet Union.
Shultz went to great lengths five weeks ago to spell out Reagan's views in seven and a half hours of meetings in New York with Soviet Foreign Minister Andrei Gromyko. Shultz made clear that if the Soviets modified their behavior in the realms of defense spending, moves into the third world, and the repression of dissidents, then it would receive a positive response from the Reagan administration.
Some analysts outside the administration, such as Marshall D. Shulman, head of the Russian Institute at Columbia University and a former top adviser on Soviet affairs in the Carter administration, say the Soviets are entering a ''fluid'' period. It's a time when Kremlin behavior can be profoundly affected by creative American diplomacy, including perhaps new arms control initiatives.
White House officials insist that Reagan intends to stick with the major arms control proposals he's already made.
For some time prior to Brezhnev's passing, the President was supervising the drafting of an arms control speech for possible delivery as soon as Nov. 18, the first anniversary of his ''zero option'' proposal concerning medium range nuclear missiles based in Europe. In the new speech, Reagan is expected to propose ''confidence building'' steps aimed at reducing the possibility of accidental war or surprise attack by either superpower. Two such steps would be to expand the exchange of data on strategic forces between the two nations and to give more advanced warning of practice missile launches. Now he has the opportunity to turn those proposals into a gesture of good will to a new Soviet leadership.