In all reason and logic one would expect the men in the Kremlin to be taking advantage of the present trough in United States-Soviet relations to try to improve their own relations with China.
One of the remarkable things about world events this summer is that Moscow has done no such thing.
This week we learn from the Peking Review, an English-language weekly published in Peking, that China's latest ''mission to Moscow'' came home with empty hands. The Soviets apparently are in no mood to pay a price for getting back into even ''normal'' relations with the world's most populous country and the Soviet Union's biggest and most important neighbor.
The Soviets and Chinese have been groping toward a reasonable relationship with each other ever since 1969. Those relations had been broken during the so-called Cultural Revolution in China when a street mob besieged the Soviet Embassy and manhandled some of the Soviet diplomats inside. The Cultural Revolution turmoil subsided in 1968. In 1969 the first overtures were made, and Soviet Prime Minister Alexei Kosygin met briefly with Chinese Premier Chou En-lai.
Nothing came of those overtures until last year when a series of exploratory meetings took place, alternating between Moscow and Peking. The first substantial result came on March 4 of this year when a Soviet passenger ship steamed into Shanghai for the first time in 20 years. A week later, on March 12, a Chinese delegation arrived in Moscow for the fourth in the series of Sino-Soviet talks. The Chinese delegation remained in Moscow until March 26, but went home with nothing to report except a decision for a modest increase in Sino-Soviet trade which had become almost negligible.
President Reagan visited China from April 26 to May 1. Obviously, Moscow found both the visit and the improvement in Sino-US relations that the trip expressed to be unpleasant. Moscow had arranged before the Reagan visit to send a top Soviet diplomat to Peking immediately after Reagan left. He was due there on May 10.
But on May 9, when the Soviet mission in Peking was still expecting the visit the next day, Moscow announced that the trip had been canceled. The only official explanation was that preparations had not been completed. That visit was to have been by a deputy Soviet prime minister, Ivan V. Arkhipov. He would have been the highest Soviet official to talk to the Chinese since 1969.
The Chinese were obviously puzzled, and curious. They arranged to send their own Soviet expert, Deputy Foreign Minister Qian Qichen to Moscow. He arrived on June 30 and flew back to Peking on July 5. On July 9 the Peking Review printed its report of ''no progress.''
All of which can only mean that the men in Moscow are as uninterested in improving relations with China as they are in getting back into serious arms control talks with the US. In the process they are ignoring or flouting the axiomatic rule in diplomacy that one country should not allow itself to be in bad relations with the two other most important powers on earth at the same time.
It took President Reagan three years to decide that he wanted improved relations with China. It was a major departure from his own ideological background to make that trip to Peking in April. His reluctance gave the men in Moscow a clear opportunity to seek to win China back into a favorable relationship. This is the week when it seems fair to conclude that they never made a real effort.
One obvious reason is that the Chinese price comes high. The Chinese have consistently required as a precondition to restoration of full normal relations that the Soviets:
1. Reduce their military forces along the Chinese frontier.
2. Withdraw from Afghanistan.
3. Cease supporting the Vietnamese, particularly in the Vietnamese occupation of Kampuchea (Cambodia).
In diplomatic quarters it is said that the Soviets have played around with partial concessions on some or all of these points, but never far enough to be tempting to the Chinese. Essentially the story seems to be that China is asking for a Soviet withdrawal from those military positions from which it could launch an invasion of China from north, west, and southeast.
Chinese insistence on the three conditions for improved Sino-Soviet relations would appear to mean that so long as Deng Xiaoping is in control in Peking, the Chinese will continue to operate on the assumption that they can do better for themselves in the context of a friendly relationship with the US than by returning to their earlier special relationship with Moscow.
The American relationship is not proving to be all sweetness and light for them. They signed an agreement for American help in developing their nuclear power industry while President Reagan was in Peking.
But implementation of that nucler power agreement has been held up since then by differences over nuclear nonproliferation. Washington wants to be sure that the Chinese will not allow the byproducts of their nuclear reactors to get into third party hands.
The head of the US Arms Control and Disarmament Agency, Kenneth Adelman, has been in Peking to try to straighten out this matter, but there are still difficulties. And the American market is by no means as open to Chinese goods as the Chinese think it could be.
There are problems in the relationship. But, limited as it is, the Chinese apparently think it's a better deal for their long-term economic development than a new relationship with Moscow while the Soviet guns point at them from along the world's longest land frontier, from Afghanistan, and from Vietnam.
Had the Chinese wanted to move back from Washington toward Moscow, their chance was before President Reagan finally committed himself by his own trip to Peking in April.
The end result seems to be that so long as Deng calls the signals in Peking, the Chinese will favor the American orientation over a revived opening to Moscow.