Without knowing the full facts, it is impossible to assess the defection of Chinese tennis player Hu Na and her request for political asylum in the United States. However, it is to be hoped that the incident will not be allowed to add to current tensions in US-China relations. Peking has demanded that Miss Hu be returned. The Chinese government should be assured that US authorities will make their determination impartially and act on the basis of US law as it applies to all countries.
The American people, of course, will always have a sympathy for anyone wishing to leave a communist nation. But this does not mean they do not value the cultural, sports, and other ties which have developed with the People's Republic of China in recent years. These ties have benefited both countries and should be preserved and nourished.
Unfortunately, relations in general are on a somewhat rocky road because of the controversy over Taiwan. To its credit, the Reagan administration is trying to work out a compromise formula on the issue of arms sales to Taiwan. But the President undercuts this effort when he declares in public, as he did the other day, that ''we are not going to abandon our long-time friends and allies on Taiwan.'' Allies? That kind of incautious language is precisely what feeds Chinese pique and plays into the hands of hard-liners who oppose Deng Xiaoping's opening to the West.
Clearly the US and China are confronted with a dilemma requiring each to be more sensitive to the problems of the other. The Chinese perhaps fail to understand adequately the political constraints on the Reagan administration and the President's need to placate the influential right wing of his party. Appearing to leave Taiwan in the lurch could jeopardize his political support. Hence the periodic need to reaffirm friendship for Taiwan.
The Americans, for their part, may not appreciate the depth of China's feeling about what it regards as a part of its territory. Taiwan raises the issue of territorial integrity and national self-respect - a hard issue for any proud country to compromise on.
Moreover, the American public needs to be aware of political dynamics in China. There remain powerful groups within the Chinese military and the Communist Party which resent China's estrangement from the Soviet bloc and which oppose Deng's policies of modernization, rejection of Maoist doctrine, and rapprochement with the US. Many no doubt would like to reverse the ''Dengist revolution'' and are ready to exploit the Taiwan question to challenge Deng's leadership.
This perhaps accounts for the Chinese leader's recent warnings about the decadence of Western capitalism and gestures toward the Soviet Union. Could he be protecting his political flanks, just as Mr. Reagan is covering his?
Neither side should give up trying to establish a stable relationship based on mutual self-interest. The US clearly cannot leave Taiwan - a long-time friend - undefended. But there is serious question that Taiwan needs to rely indefinitely on the US for sophisticated arms when (1) it can obtain defensive weapons from other Western countries, (2) it can manufacture and sell arms itself, and (3) it is virtually impervious to an attack from the mainland.
Overshadowing this problem is the continued urgency of developing ties with a nation that is strategically important to the US and will one day be a strong force in the world. It cannot but delight the Soviet Union that the Reagan administration is having problems not only with its allies but with China. The administration would be short-sighted to give it that satisfaction for long.