Arms sales to Taiwan take bloom off US-Sino relations

Ten years after the Shanghai communique approved by President Nixon and Chinese Premier Chou En-lai, Sino-American relations are blooming in all directions but one - US arms sales to Taiwan.

Mr. Nixon called his visit to China ''a week that changed the world.'' At the time of his visit, the statement was more promise than reality. Today, global strategic relations and the east Asian regional balance are so different from what they were 10 years ago that it is hard to imagine there ever was a time when China was largely absent from the international community.

The Shanghai communique was the symbol and to a large extent, the key, to China's return from 30 years of self-imposed isolation from the world community. Now China is in the United Nations, the World Bank, the International Monetary Fund, and the Olympics. Its trade with the US, Western Europe, and Japan steadily increases.

China's voice is heard with respect in the councils of the world. That voice has been, by and large, constructive, not disruptive, on issues as diverse as family planning and the protection of the environment.

One Chinese goal - the formation of a worldwide coalition against Soviet ''hegemonism'' - has not been realized. But China, the US, Western Europe, and Japan have very similar views on the nature of the Soviet threat. In a number of areas - Afghanistan and aid to Pakistan - China and the US have taken mutually reinforcing actions.

The one stumbling block in the way of better Sino-American relations - and of better coordination of global strategy to counter Soviet expansionism - has been and remains US arms sales to Taiwan.

China is in the midst of delicate negotiations with the US aimed at obtaining a commitment that the arms sales will diminish and eventually cease. Both sides are tight-lipped about the discussions but say that unless a solution is found, China may downgrade diplomatic relations with the US to charge d'affaires level.

The fact that Sino-American discussions continue, and that the Chinese media has moderated its public stance since President Reagan's year-end decision not to supply advanced fighter planes to Taiwan, shows the care Chinese leaders are taking not to let the dispute get out of hand. But because of the emotional nature of the sovereignty issue, they have made clear that their room for maneuver is limited and the downgrading of relations is a real possibility.