The accession of a new ruler in Moscow immediately caused many to ask whether just possibly there might now be at least some abatement of tension between Moscow and Washington.
The answer is that yes, there is and will be for a short time some slight let up in the tension. But very little in the long run will come of it.
There will be brief and slight reduction simply because the outside world will want to take time to measure and to gauge the quality of the new leadership in Moscow. Also, no new leadership in Moscow would be inclined to do anything radical until it settles into the seat of power. Caution on both sides is likely until each begins to think that it understands the other.
After that the relationship between Moscow and Washington will be shaped, as it has for many years already, by one basic condition which is not likely to change for some time.
That basic condition which dominates thinking in each of the two superpower capitals is that there are only two superpowers in the world today, and there are not likely to be other superpowers for some time.
History is explicit on the difficulty which two superpowers have in accommodating peacefully to each other. When there are only two there is mutual suspicion, rivalry, and frequent conflict.
A classic example was the rivalry in ancient times between Rome and Carthage. The Mediterranean world was simply not big enough for the two. Both assumed that one would destroy the other. Carthage nearly won, but in the end Rome was the winner, and literally wiped out Carthage.
A more recent example was the rivalry between France and Germany. It lasted from the middle of the 19th century until World War II broke Germany up into two parts. After that the rise of Soviet and American power made other rivalries secondary.
Moscow's new leader, Yuri Andropov, speaks fluent English. That is a good thing in one respect. It means that he will probably be better able to appraise the actions and positions of the United States more accurately than have his predecessors who did not speak or understand English.
For that reason Mr. Andropov is probably less likely than was Nikita Khrushchev to misjudge American reaction to Soviet action. Mr. Khrushchev thought he could get away with planting his missiles in Cuba. His mistake not only humiliated his country. It also cost him his job.
But greater knowledge of the other, on both sides, cannot eliminate the elements of rivalry which cause tension.
In theory General Secretary Andropov and President Ronald Reagan ought to be able to sit down together, talk it all over, and, in effect, agree to share the world on a fair basis and without friction. But suppose that they did sit down together. What would be the first subject Mr. Andropov would bring up? Poland, of course. And what would Mr. Reagan toss back in exchange? Cuba, of course.
To any Russian it is monstrous that the Americans encourage the Poles to reach for freedom. But any American is bound to think that the Poles should have their freedom. President Reagan must speak for the Poles and must want to punish the Soviets for imposing military rule on the Poles. He must do so partly to satisfy the large Polish community in the US. He must also do it to satisfy a general American sense of the right of people to self-determination.
Yet to any Russian (particularly to Russians as distinct from other kinds of Soviet citizens) encouragement to Poles threatens the security of both Russia and the Soviet Union. Remember that the Czars took much of Poland during the 18 th-century partitions of that unhappy country. The Grand Duchy of Warsaw was a formal part of the Russian empire. Poland today is at least ruled by a Polish general, even though under Soviet discipline.
Then there is Cuba. Any American resents having Soviet troops in Cuba and Cuban troops doing imperial service for Moscow in Angola and Ethiopia. The Soviet presence in Cuba is a threat to American security. But to the Soviets it is only right and proper that Moscow should befriend a ''national liberation movement'' in Cuba against US domination.
Mr. Reagan dare not give up encouragement to the Poles, but to encourage them is regarded as hostile to their interests by the Soviets. Mr. Andropov will not dare to give up aid to Cuba. It would undermine Soviet credibility as friend and ally. But Soviet help to Cuba is an act of hostility toward the US in American eyes.
The two superpowers are rivals. They will inevitably continue to be rivals as long as they are the only two superpowers in the world. Their rivalry will continue to be restrained as it has been for several years by mutual fear of nuclear disaster. But the rivalry will continue until and unless the power structure of the world is changed.
Other superpowers may rise. The Soviet Union might decline and cease to be a superpower. But until such a change occurs, as it may, but not tomorrow, the Soviet Union and the US will be rivals, jealous of and fearing each other and finding it difficult to avoid going to war against each other.