TOKYO, SEPT. 3 -- Casting a wary eye over their shoulders at American public opinion, embarrassed officials of the Japanese government today said they are facing "unexpected delays" in providing promised assistance for the U.S.-led multinational military force on the Arabian Peninsula.

The highly disciplined economic superpower that works with well-oiled precision in global trade markets has been fractious and sputtering in its response to the Persian Gulf crisis. Union and corporate leaders are balking at some of the promises Prime Minister Toshiki Kaifu has made to Japan's allies, and the Kaifu cabinet is arguing openly over how much aid Japan can provide within the framework of its pacifist constitution.

"This endeavor is not without difficulties," said a haggard Yukio Okamoto, a mid-level Foreign Ministry bureaucrat who has been struggling around the clock -- in vain, so far -- to get Japan's formidable auto industry to send a shipload of four-wheel-drive vans to U.S. forces in the Mideast. "We will not be able to deliver the {vans} as quickly as we had hoped."

Kaifu's two-week-old commitment to dispatch an advance team of medical personnel also remains unfulfilled. Kaifu promised to assign about 100 medical experts to the allied force, but Foreign Ministry spokesman Taizo Watanabe said today that there have been "unexpected delays" in recruiting a volunteer medical team.

Kaifu expanded Japan's offer last week to include $1 billion in supplies and services for the Mideast force. Before the new proposal was made, U.S. congressional leaders and diplomats had voiced impatience with the pace and scope of Japanese aid offers, and polls reflected similar sentiments among most Americans. President Bush last week made a personal appeal to the prime minister for increased assistance, but after Kaifu announced the expanded package, Bush expressed satisfaction.

Kaifu and his aides have shown acute awareness of the criticism of Japan's limited participation in the multinational force. To deal with it, Foreign Ministry officials today sat down with American reporters and complained that the Japanese effort has been misunderstood.

Although Japan is more dependent on Mideast oil than the United States and many European nations, its promised $1 billion contribution to the force is smaller than that of several other countries. At current estimates, the United States will spend well over that figure every month it keeps troops on the Arabian Peninsula. While the United States and other countries are sending thousands of military personnel, Japan's only manpower commitment has been the 100-member medical team.

To the Japanese, however, Kaifu's promise that Japan will contribute to the Mideast effort involves a national turnabout of historic dimensions, a major break with the largely hands-off foreign policy Japan has maintained since the end of World War II. It is this, rather than the size of the aid package, that officials have called important.

The Foreign Ministry's Watanabe called the promise "a breakthrough" in policy. "This is the first {time} in our postwar history that we have taken such a role in a region far away. This venture would not have been conceivable some years ago."

It may not be conceivable today, either. Leaders of the seamen's union are arguing that materiel for the war zone should not be carried in Japanese ships. Officials at some auto companies and other manufacturing firms have expressed concern that shipping Japanese goods to the allied force may endanger Japanese men held hostage in Iraq.

Today, the Ministry of International Trade and Industry called in leaders of six big industry associations and ordered them to get serious about producing the goods Kaifu has promised. According to Foreign Ministry officials, the trade agency told the corporate leaders that Japan's commitment to aid the U.S. forces in the gulf should have priority over regular business.

Meanwhile, there is a running dispute here as to how much and what kind of aid Japan can send to the Mideast under the constitution. Written for the Japanese by the American occupation force after World War II, it appears to preclude sending military forces overseas.

But some members of the national legislature, or Diet -- as well as members of Kaifu's cabinet -- have argued that Japan could legally send part of its 250,000-member armed forces overseas in a supportive role.When Kaifu last week promised to send materiel, money and medical supplies to the gulf region, he also proposed legal changes that would make it easier in the future for a Japanese government to send troops in conjunction with a United Nations military force but that would not require a constitutional amendment.

Polls suggest, though, that most Japanese people support existing curbs on military involvement.