Japan's Foreign Policy Toward Vietnam 1978-1992

Wikipedia has related information at Japanese-Vietnamese relations

When the United States withdrew from Vietnam in 1973 and South Vietnam fell to the North Vietnamese Army in 1975, US leadership in Asia suffered a severe blow. The power equation in Asia again shifted in 1978, when President Carter announced diplomatic normalization with China and Tokyo signed the Peace and Friendship Treaty (PFT) with Beijing. When Vietnam invaded Cambodia in December 1978, under claims of protecting ethnic Vietnamese, Tokyo's reaction diverged from the responses of Washington and Beijing. Because of the changing power relationships in East Asia, Japan's foreign policy toward Vietnam differed from the US policy when Tokyo acted in its own self interest to steer a course among the United States, China, The Association of Southeast Asian Nations (ASEAN), and Vietnam. An investigation of Japan's foreign policy toward Vietnam during this period could provide an understanding of the larger bilateral relationships of Tokyo and Washington and Tokyo and Beijing, while highlighting regional and domestic factors that caused Tokyo to choose this independent middle course.