Tokyo — Japan has just discovered how hard it is for an outside power to have any influence in the Middle East. The region has been a major foreign policy target for Tokyo this year. Japan hoped it's growing economic stake would help it to shape events there.
In August, for example, Foreign Minister Shintaro Abe put his prestige on the line in visiting both Iran and Iraq to urge them to terminate their 37-month-old war quickly.
Although he insisted Japan did not intend to act as a mediator, Foreign Ministry officials at the time said Tokyo had strong links with both Iran and Iraq, making it the only country in the Western bloc capable of undertaking such a difficult role.
But this assessment has proved unduly optimistic, following Iraq's official warning that it might bomb an Iran-Japan petrochemical complex in the Iranian port of Bandar Khomeini. Foreign Minister Abe at first told reporters he considered the warning had an element of psychological warfare and that the government would not overreact.
Ministry sources believed the Iraqi warning was primarily a ploy to get Japan to apply further pressure to Iran to go to the conference table and terminate the Gulf war.
The Japanese government responded by urging Iraq to spare the Bandar Khomeini complex but was met with a second and ''final'' warning by Iraq.
Japan then began to take the Iraqi threat more seriously.
For a while Foreign Minister Abe was said to be considering an urgent visit to both countries. But with a heavy diplomatic schedule in front of him, including the visit of President Reagan this week, he finally decided to send Deputy Foreign Minister Toshijiro Nakajima to try to defuse the Gulf tensions.
Mr. Nakajima was not able to secure an Iraqi agreement to spare Bandar Khomeini, but Abe still says he believes Iraq would try to avoid attacking the plant to maintain friendly relations with Japan. Nakajima expects to visit Iran in mid-November.
Foreign Minister Abe told reporters last week that Japan had made ''utmost efforts'' to persuade Iran to accept a United Nations Security Council resolution urging an end to the conflict with Iran and safe passage of vessels in the Gulf.
He expressed regrets that Tehran had not been able to accept the resolution.
Diplomatic sources said Abe would lose considerable face now if Iraq ignored his repeated requests and went ahead with the threatened bombing.
At the same time, they said, the Tokyo government had to face the reality that it is almost totally unequipped to influence events in the region. Lacking any military or political leverage, it has to rely strictly on its economic role , which simply is not sufficient to divert any country from its chosen course.
Although an acknowledged member of the Western bloc, Japan has managed to maintain an image as a political neutral in the Middle East, making it virtually unique in being able to maintain friendly ties with both Iran and Iraq throughout the three-year Gulf war.
But foreign ministry officials now concede this growing economic influence is creating greater pressure to take some sort of definite political stand. While urging Iraq to spare Bandar Khomeini, for example, the Japanese have been applying pressure on Iran not to carry out a threat to close the Strait of Hormuz through which a good part of the country's oil supply comes.
With 70 percent of its oil coming from the Middle East, Japan is extremely vulnerable to any sort of instability. The same increasingly applies to its economic investment which is widespread and growing fast. (Direct Japanese investment in Iran at the end of fiscal 1982 was $2.5 billion, 4.7 percent of total overseas investment, according to the finance ministry. Unofficial estimates run twice that amount.)
Bandar Khomeini is a case in point.
The project, originally supposed to cost $3.5 billion, was halted by the outbreak of the Iran-Iraq war, when it was 85 percent complete.
At that stage the Iranians and their Japanese partners - led by the Mitsui group of companies - had spent $2.5 billion equally between them. After protracted on again-off again negotiations, the two sides signed a fresh agreement last July to complete the project despite continuation of the war. The big difference was that Iran agreed to cover all remaining costs, with the Japanese side providing only technical assistance.
A Mitsui spokesman said, however, there was no chance of any Japanese being sent to the project site as long as the threat of bombing continues. Business analysts said Mitsui would suffer very little from any damage to the petrochemical complex as it is well covered with insurance.
The main victim, everyone seems to agree, would be Japan's desire to play an influential, independent political role in such a traditionally volatile area as the Middle East.
At this stage, many observers feel, the Japanese government can do little but appeal for restraint between Iraq and Iran - and hope for the best.