Tokyo — Friendship between the United States and Japan is "the most important bilateral relationship in the world -- bar none," Ambassador Mike Mansfield said emphatically.
In a wide-ranging interview, the tall, craggy-faced former senator from Montana made the following points:
1. The United States and Japan "share a joint responsibility for the Pacific Basin and the nations along its rim," in which Japan's role "is more economic -- not so much defense."
2. On defense, "I think they [the Japanese] can and should do more, but not through pressure, demands, or the like. . . . In their own way, in their own time and in line with their own resources they will do, I think, what we want them to do, on their own responsibility."
3. In the Iranian and Afghan situations, the Japanese "have been our best allies and partners, and the only ones who paid a price in the process." Mr. Mansfield cited Iran's cutoff of oil amounting to 13 percent of Japan's imports and Japan's loss of lucrative Soviet pipeline contracts to France and West Germany as examples.
4. On trade, Japan has almost always "made efforts to accommodate itself to our needs, to our criticisms and complaints" through a long succession of disputes from textiles through color television to steel and most recently, automobiles.
Japan's agreement to reduce car exports to the United States from 1.82 million cars last year to 1.68 million cars this year has "prevented a very possible enactment of protectionist legislation beneficial to no one and harmful to all," Mr. Mansfield observed.
Japan is "far and away our No. 1 customer" for agricultural products, the ambassador continued. Last year, Japan imported close to $6.1 billion of grain and other agricultural products from the United States.
Referring to criticism that Japan's security treaty with the United States is one-sided, in that it obligates the United States to defend Japan in case of attack, but not Japan to defend the United States, Mr. Mansfield asked:
"Is it one-sided? We have the use of bases and airfields out here, at no cost to us. We have the Japanese appropriating $1 billion per year for the upkeep of United States forces, cost-sharing, housing, and the like. We have the Japanese willing to increase that figure.
"If we didn't have the security arrangement with Japan, where would our forward bases in our own defense be located? Guam. Hawaii. We're out here to stay!"
Mr. Mansfield would like Americans to view the current furor in Japan over whether American warships visiting their country do or do not carry nuclear weapons against the background of all these factors. Former Ambassador Edwin O. Reischauer precipitated the controversy by stating that for 20 years American warships had entered Japanese ports without divesting themselves of their nuclear weapons, as the Tokyo government claimed they were doing.
The return of the aircraft carrier Midway to Yokosuka, its home port, June 5 will be a major test of Japanese feelings on the nuclear issue. Many Japanese suspect the Midway of carrying nuclear weapons, and opposition parties from the Socialists to the Communists have been trying to whip up demonstrations and other protests against the Midway's return.
Mr. Mansfield refused to be drawn into the nuclear controversy, beyond repeating Washington's longstanding policy of neither confirming nor denying the presence or absence of nuclear weapons anywhere in the world. But he is clearly concerned about the effect this controversy will have on Japanese- American relations as a whole.
It comes on top of a series of unrelated incidents that followed each other in quick succession -- a collision between an American nuclear submarine and a Japanese freighter (the freighter sank), domestic controversy over the meaning of the word "alliance" used in a communique after Prime Minister Zenko Suzuki's very successful visit with President Reagan in Washington at the beginning of May, and the cutting of Japanese fishing vessels' nets by American (or perhaps Soviet) warships during a recent exercise in the Sea of Japan.
What lesson is to be drawn from these incidents, the cumulative effect of which could be to cause a dangerous rise in emotional tensions between the people of Japan and the United States?
Mr. Mansfield, sitting upright in his office armchair, paused long.
"We'll have to understand each other better," he said softly, then paused again.
"We'll have to quit finding fault with one another. We'll have to act as true equals. We'll have to recognize we share a joint responsibility for the Pacific Basin and the nations along its rim -- more economic, not so much defense.
"My one aim, insofar as I can do it, and insofar as this embassy can do it, is to strengthen the bonds of friendship and partnership between our two countries to the point where they become unbreakable."
Mr. Mansfield, who as Democratic majority leader was for many years one of the most powerful figures in the United States Senate, was appointed ambassador to Japan by President Carter in 1977 and asked to stay on by President Reagan early this year.
"We were halfway through our packing," the ambassador recalled, when Mr. Reagan, then still President-elect, called to ask the Mansfields to stay on. "I was delighted to say yes, because there's a job still here to be done."
Mr. and Mrs. Mansfield have been one of the most popular and effective ambassadorial couples to have served in Japan. Analysts of Japanese-American relations are almost unanimous in their opinion that, whatever the ups and downs between the two countries have been during the past four years, tensions would have been far more severe without Mr. Mansfield's firm but nonblustering and fair- minded approach, without the influence he has been able to exert behind the scenes, both in Tokyo and in the labyrinthine political corridors of Washington.