Japan is striving to maintain a dialogue with Vietnam but has no intention of making substantive steps for improvement of relations until Hanoi pulls its troops out of Kampuchea.
Meeting ambassadors from the Association of Southeast Asian Nations (ASEAN) here last week, Foreign Minister Shintaro Abe repeated this policy as he reported on a visit to Hanoi last month by a senior Foreign Ministry official.
Hiroshi Hashimoto, director-general of the ministry's Asian affairs bureau, met a number of senior Vietnamese government officials to discuss bilateral and international issues, with the emphasis very much on the Vietnamese military presence in Kampuchea. His visit fulfilled Japan's desire to keep open the channels of communication with Hanoi but did little to narrow the major differences between the two countries, ministry sources said.
In his meeting with the ASEAN envoys, Foreign Minister Abe was reported as saying withdrawal of all Vietnamese forces from Kampuchea was a prerequisite for peace in Southeast Asia, and without it Japan would continue to maintain a freeze on economic assistance to Vietnam imposed after its invasion of Kampuchea in 1979. But he stressed that Japan desired to continue its dialogue with Vietnam to maintain the pressure on Hanoi to change its policy.
Japan seems to have ambitions to act as a bridge between Vietnam and the ASEAN states in promoting regional peace.
According to usually well-informed sources here, Vietnam entertained similar hopes, which turned to bitter criticism after Prime Minister Yasuhiro Nakasone visited ASEAN last spring and strongly backed the regional bloc's stance on the Kampuchean issue. The visits to Japan last November by President Reagan and Chinese Communist Party chief Hu Yaobang also seem to have added to Vietnamese suspicion of Japanese good intentions, the sources said.
The Hashimoto visit to Hanoi clearly showed there was no immediate prospect for an improvement in the political climate surrounding Indochina, they added. Japan-Vietnam relations have been far from good since 1979, when the Tokyo government froze its scheduled economic assistance to Hanoi because of the intervention in Kampuchea. Since then, Japan has acted in close concert with the five ASEAN members in trying to solve the problem.
Despite the difficulties, a senior Foreign Ministry official has been sent to Hanoi for the past three years now to keep open at least a limited dialogue with the Vietnamese leadership. Vietnamese Vice-Foreign Minister Ha Van Lau visited Tokyo last March in return, reaching agreement with his Japanese counterpart that the two countries should try to improve bilateral relations, but making absolutely no progress on the Kampuchea issue.
Japan would certainly like to see some progress made as soon as possible. It sees itself in a unique position as acting as a bridge between Vietnam and the West.
The relations it maintains with Hanoi also enhance its prestige, enabling it to provide valuable information to the United States and other Western allies about what is going on in Vietnam today, knowledgeable Western diplomatic sources observed.
Other sources said Japan also had hopes that it could bring ASEAN and Vietnam closer together to promote permanent peace and stability throughout the region. At the same time it is pouring billions of dollars into ASEAN to strengthen its ability to withstand any further expansion of the Vietnam-Soviet Union axis.
When the Tokyo government made its pledge of economic aid to Vietnam in 1978 - a grant of 16 billion yen (about $68 million) and another 20 billion yen (about $85 million) in loans - it hoped this would lessen Hanoi's dependence on the Soviet Union and bring it closer to the Western/ASEAN camp.
Now, analysts say, the freeze imposed in 1979 when less than half the money had been handed over has driven Vietnam more firmly into Moscow's arms.
Japan is clearly worried about the Soviet Union's growing military presence adjacent to the key shipping routes that provide it with the bulk of its vital raw materials like oil. Foreign Ministry sources said one of the aims of Mr. Hashimoto's trip was to try to ascertain the extent of Soviet use of Vietnamese military bases, especially Da Nang and Cam Ranh Bay, which were developed by the US during the Vietnam war.
The government is worried by the increasing number of Soviet warships visiting Cam Ranh Bay, as well as the apparent basing of a number of TU-16 and TU-95 bombers, equipped with air-to-sea missiles, at Da Nang. These could easily disrupt Japan's trade routes, should an emergency occur, military sources said.
Despite the freeze on economic assistance, early in December Tokyo approved $ 100,000 in emergency aid for victims of a recent typhoon in Vietnam. In 1982, it provided about $120,000 in medical assistance to a hospital in Ho Chi Minh City (Saigon) originally built with Japanese economic assistance. Officials here stressed this was purely ''humanitarian assistance'' and presaged no weakening of Japan's determination to use the economic weapon to force Vietnam out of Kampuchea.
Despite all the difficulties on a governmental level, Japan remains Vietnam's biggest private trading partner.