Tokyo — The Japanese government announced a decision yesterday to take nonmilitary steps to aid Western security efforts in the Gulf. The Japanese hope to quell criticism of their failure to assist the safeguarding of oil shipping from the vital Gulf area, despite their dependence on oil supplies from the region. Last month in New York, Prime Minister Yasuhiro Nakasone promised President Reagan that Japan would take some action the end of this month - when the prime minister's term ends.
The government and the ruling party rejected the option of sending mine sweepers and Coast Guard vessels to the Gulf, a move considered in probable violation of Japan's ``peace'' Constitution.
Japan instead will install a shore-based navigation system to aid ships to avoid mined waters and will increase economic aid to Gulf nations and United Nations peacekeeping efforts. Simultaneously, the government said it will seek ways to compensate the United States for its security role by increasing the Japanese contribution to the maintenance of US armed forces in Japan.
The navigation system utilizes shore-based radio stations to pinpoint the the location of an off-shore vessel. With such a highly accurate fix of their position, tankers will be able to more easily avoid waters know to be mined. Japan will fund the construction of several stations, at a cost of about $20 million each.
The aid, which the government hopes will contribute to overall stability, will go to Oman and Jordan. Oman will receive $200 million in concessional loans for economic development projects while $300 million will go to Jordan. The government also has earmarked $10 million to aid the efforts of the UN Secretary-General to mediate an end to the Iran-Iraq war.
Some in the ruling Liberal Democratic Party (LDP) favored a bold move to dispatch mine sweepers. However, Japan's US-imposed Constitution bars the use of military force except for the defense of Japan's own territory. Mr. Nakasone last month offered the view that the mine sweepers' defensive role would technically allow their use in the Gulf.
But even Nakasone hesitated to go beyond that theoretic formula. ``There would be a real fuss about that,'' predicted Motoo Shiina, an LDP member of parliament. ``In the opposition parties - even in LDP - people would say that is very suspicious from a constitutional standpoint.''
The government concluded that such an unprecedented step would be politically impossible, but there was also a strong feeling that simply providing money would not be seen as sufficent. The new Gulf package reflects an attempt to mix financial help with some form of direct, though nonmilitary, aid.
The government anticipates that the Gulf policy will gain the support of the Reagan administration.
Japan also delivered another key security policy decision which won the praise of the Reagan administration and congressional critics. Last week, Yuko Kurihara, the director of the Japanese Defense Agency, said that Japan would abandon plans to build its own domestic model of a fighter aircraft. Instead, it will choose a variant of a US fighter.
Congressional leaders and Pentagon officials had urged the purchase of the US plane, arguing it would be a more cost-effective use of Japan's limited defense resources. The issue had been deadlocked in the Japanese Defense Agency until recently when Mr. Kurihara won support for the view that going through with domestic development would seriously harm US-Japan relations.