Nothing is as crucial to America's interests in Asia as its ties with Japan. Hence it is all to the good that Japanese Prime Minister Yasuhiro Nakasone and President Reagan have had a face-to-face meeting to try to dispel the sourness that has crept into relations between their two countries. The leaders appear to have hit it off well, and this should help to get this key relationship back on track.
The Washington get-together has not resolved the issues rankling the two countries, above all America's frustration over inability to gain access to the Japanese market for US exports. No initiatives emerged. Economic conflicts and defense problems will continue to be the subject of bilateral talks. But the right atmospherics can be a help in reaching substantive agreements, and with both men voicing determination to resist trade protectionism and strengthen the US-Japanese security tie the atmospherics have improved.
Mr. Reagan cannot but be pleased with the new Japanese prime minister. Mr. Nakasone is impressive. He is certainly a stronger and more articulate leader than his predecessor. Courageously he has already taken steps to shore up bilateral ties - putting through an increase in Japanese defense spending, lowering trade barriers on a few US products, and committing his government to long-term economic aid to South Korea.
We say courageous because Mr. Nakasone takes a political risk with such measures. He has only a narrow power base, for instance, and must reckon with powerful figures in the Liberal Democratic Party as he tries to rebuild his party's shaky structure. He must deal, too, with the insular attitudes of the Japanese people who, for all their eagerness to adapt Western ideas and thrust outward into the world economically, still resist opening their doors to American and other foreign products and to spending more on defense while the social budget is being cut back. By going so far as to speak publicly of the Japanese-US ''alliance'' - a word often shunned by Japanese politicians - Mr. Nakasone showed just how pro-American he is.
This is not to suggest that the US does not have legitimate complaints. For decades American businessmen have had trouble penetrating the Japanese market, and, although it can be said (as the Japanese do) that they have not displayed the ingenuity and enterprise needed to sell their products abroad, aggravating barriers remain in the form of tariffs, complex regulations, and the general clubbishness of the Japanese business community. A trade balance in Japan's favor of $20 billion is unreasonably high.
Defense is also an urgent issue. There is, of course, much to be said for not pushing Japan into rearmament, perhaps to the point of acquiring nuclear weapons. The US security umbrella has well served the goal of stability in East Asia, permitting Japan to direct its tremendous energies into economic pursuits and relieving its neighbors of anxiety about a resurgence of Japanese militarism. Yet times change and needs change. With Japan now the second industrial power in the world and with the Soviet Union fast expanding its military presence in Asia, it seems only prudent that Japan play a bigger role in defense of the region. At present Japan still spends less than 1 percent of its gross national product on defense - as compared with, say, 4.3 percent for West Germany or 5.3 percent for Great Britain. Surely it can do better than that .
Sharp disagreements remain, and compromises will not be achieved overnight. It will take patience and understanding for the US and Japan to build on the better atmosphere created as a result of the Nakasone visit. Each side must carefully weigh the impact of its demands on the other. The Japanese surely realize that failure to ease their trade barriers will only fuel protectionist measures in the US and hurt both parties - and indeed the whole world economy - in the long run. The Americans have to be sensitive to political repercussions in Japan if faster defense commitments create a public furor.
Mr. Nakasone's foray into Washington may not have settled matters. But it should make progress possible.