When Japanese Prime Minister Masayoshi Ohira arrives here a week from now for talks with President Carter, he is expected to warn strongly against the use of American force in Iran.
Japanese diplomats say their country is willing to pay a price for its alliance with the United States. Japan will go along with the economic and diplomatic sanctions against Iran that were decided on by the European allies April 22.
But the diplomats assert that should the US go beyond such sanctions and use military force against Iran, possibility through a blockage that would include the mining of Iranian harbors, it would be likely to produce highly negative consequences for the Wester allies, both inside and outside Iran.
The Western Europeans are said to be delivering a similar message to President Carter: no military action -- unless the American hostages being held in Tehran are harmed. But Mr. Ohira will be the first to the allied leaders to convey that message firsthand. Japan's warning against the use of military force carries a special urgency because the Japanese are more dependent on oil imports from the Persian Gulf than are any of the other allied nations.
A remarkable degree of consensus has emerged among the Western Europeans and Japanese in recent weeks. Their main concerns can be summarized in three points. They fear that US military action might well:
* Reinforce the hand of extremist elements in Iran.
* Cause an unpredictable and possibly violent reaction elsewhere in the Muslim world, thus threatening Western interests in more than just one oil-producing country.
* Drive the Iranians closer to the Soviet Union. Iran has just reached an agreement with the Soviets for expanded trade, apparently to help counter the effects of planned Western sanctions. The Soviets are further offering Iran a possible detour for goods from other countries around a blockade. The detour would consist of the increased use of overland trade routes across Soviet territory and into Iran.
A West German diplomat said that one must also add to this list "a degree of doubt that any kind of military action would achieve what is the object of all this -- the safe release of the hostages." He predicted that military action would "probably endanger the hostages even further."
The West German diplomat also predicted that when it came to the use of force against Iran, most Muslim countries would side with the Iranians. A japanese diplomat said that the reaction of Islamic nations would be likely to be "quite negative" but also "so emotional that it would be hard to predict" how far it would go.
"Too much of an element of gamble is there," the Japanese diplomat said.
Both the Western Europeans and the Japanese seem to feel that by agreeing to support President Carter's economic and diplomatic moves against Iran they may be getting the President "off a hook" that was carrying him inexorably toward military action.
But the White House reaction to the April 22 decision of the European allies to impose sanctions at an early date, after a planned May 17 meeting, if the 50 American hostages ar not released by then was less than enthusiastic. Part of the White House disappointment was apparently due to the europeans' failure to set a definite deadline for their economic actions against Iran. What the Europeans are doing for the moment is imposing an arms embargo against Iran and reducing their diplomatic representation in Tehran.
White House officials at first indicated that they would have a statement concerning the European decision but then retreated into silence. At the State Department, where there was considerably more understanding for the European decision, a spokesman issued a statement welcoming it. One State Department official later said that the spokesman's statement amounted to "a pat on the back, but not an embrace -- appreciation without necessarily setting off any fireworks."
A day later, April 23, the White House finally issued a restrained statement of its own, welcoming the decision of the Europeans to invoke economic sanctions against Iran barring "decisive progress" toward freeing the hostages.
The Japanese, meanwhile, express a special need to reaffirm the strength of their alliance with the US through Prime Minister Ohira's visit to Washington April 30-May 1.
Japanese diplomats say they believe that relations with the US were badly strained last Dec. 10 when the Carter administration charged that Japan had undercut American efforts to use economic pressure on Iran by buying up Iranian oil that originally had been earmarked for the U.S. President Carter had ordered a halt to American purchases of Iranian oil last November.
But the Japanese argue that their oil companies were forced to increase their purchases because major US oil companies had drastically cut their supplies to Japan. Japan is almost totally dependent on imported oil, with a little more than 10 percent of its annual requirements coming from Iran.