The Chinese card in now being played by the only player in the world game that can play it - China. The treaty signed with Japan last week and the current foreign visits by Chairman Hua Kuo-feng are part of a large move to break, and maybe even reverse, encirclement by the Soviet Union.

For the United States, rich opportunities accompany the Chinese move - but also perils. Unless this country is aware of the perils, it could face, five years from now, the worst of all possible outcomes - a Sino-Soviet rapprochement.

The Chinese began to break out last spring when Hua visited North Korea. Immediately thereafter the North Koreans started to tilt away from Moscow and toward the Chinese line on such matters as the Soviet presence in Southest Asia and the Cuban presence in Africa.

There followed a Chinese accord with the European Economic Community embracing the strongest countries of Western Europe. Then came the visit to Peking of the president's special assistant for national security affairs, Zbigniew Brzezinski. That put the United States and China on what Brzezinski called a parallel "strategic" course.

The Japanese treaty is a major development by which Tokyo turns its economic power and developmental strategy away from Siberia and toward China. On his present trip to Rumania, Yugoslavia and Iran, Hua will undoubtedly push for even stronger resistance to Russia by countries already determined to block further expansion of the Soviet empire to the South.

To a large extent, the Chinese actions are only a logical foreign-policy extension of the basic domestic-policy decision to modernize agriculture, industry, the military and education. In order to modernize, Peking needs massive credits for investment, access to high technology both in the civilian and military fields, and the means for training thousands of young people in technical subjects.

It is already clear that the Chinese will be buying their military equipment in Western Europe. Most of their capital investment will come from Japan, along with much high technology. The United States will provide some technology and lots of training. The present prospect is that tens of thousands of young Chinese - a whole new generation, in fact - will come to this country for graduate training.

But that benign interpretation is not the interpretation that is being placed on the recent developments by the Soviet Union. On the contrary, the Russians see the Chinese girding against them and enlisting in that cause the Americans, the Japanese, the West Europeans and even the East Europeans and South Asians.

A striking instance of Soviet feeling is the view now being expressed by Georgi Arbatov of the USA Institute. Arbatov in the past, and particularly after the Nixon visit to China, has been relatively calm about the connection between Peking and Washington. But last month when I visited him in Moscow, he said: "There is no way of playing innocent games with China."

So we can expect the Soviet reaction to China's latest moves. Moscow will almost surely lean harder on Tokyo. The Russians may stiffen their position on SALT, or they might apply counter-pressures around the Chinese borders - notably in Vietnam.

That is where a truly sharp pinch could come for the United States, for if the Russians develop a military presence in Vietnam, the Chinese are apt to ask for countermoves by the United States. But this country, having suffered so much to save Vietnam from communism, would surely not be keen to intervene there for the sake of the Chinese. In the face of an American disappointment on their hottest border, the Chinese would certainly begin having second thoughts about Washington.

The danger of another Chinese flip-flop, in other words, remains serious. The Chinese have unresolved questions affecting their leadership, the regional balance of power within the army and the basic division of resources. Efforts to deal with those extremely hard problems have already caused Peking to flip back and forth between the United States and Russia. It is a foolish person who does not think another turn is possible.

But with the danger identified, certain measures to limit the risk can be taken. The Chinese ought not to be given false hope of American willingness to participate in an anti-Soviet strategy. That means withholding any delivery of weapons, and even going slow on normalization of diplomatic relations.

The Russians can be told that the nature of the U.S.- China connection is up to them. If they continue to bully the rest to the world, the United States will be more and more forced to help the Chinese mount counterpressures against the Soviet Union. If the Russians act in a less aggressive way, then this country will do its not inconsiderable bit to keep the Chinese card benign.