is the emergence of a power vacuum caused by the U.S. withdrawal from the region and the shift of the structure of rivalry from U.S. versus the Soviet Union and China to the Soviet Union versus China and U.S. The other is Japan’s rising influence in the region at the time. Japan was undergoing a rapid economic development, reviving material power and geostrategic resources such as Okinawa. In this situation, the Fukuda Doctrine reassured that despite the power vacuum, Japan would not dominate the region. Japan's consistent adherence to the Doctrine contributed to the longevity of the positive relations. Japan participated in the peacebuilding missions in Southeast Asia since the 1990s. The emphasis was put on “human security” during the 1997 Asian financial crisis, during which Japan supported social stability through economic assistance. Furthermore, Japan has also been supporting ASEAN’s community-building efforts since the early 2000s, in an attempt to strengthen its political-security and to form economic and socio-cultural communities. The Fukuda Doctrine, as Kei Koga, a researcher of the Center for Strategic and International Studies writes in his report, Transcending the Fukuda Doctrine, “has been instrumental in defining Japan’s approach toward ASEAN’s efforts to integrate politically.” Koga further argues that the current Japan-Southeast Asian relations have developed beyond socio-cultural, economic, to include political and security dimensions, and at a point where they can help shape and direct the region. Further progress is essential, considering the rise of China and the uncertainty over US-Southeast Asia policy under President Donald Trump. International and Domestic Reactions International Reactions The reactions of ASEAN countries shifted from being cautious but optimistic in August, to openly hostile at the end of 1977. If the promises could be fulfilled, the Doctrine was welcomed. In fact, The ASEAN members, regretting America's withdrawal, initially encouraged Japan to play a bigger role as long as Japan doesn't become a military threat. Nonetheless, the feeling of suspicion that Japan would not fulfill the promise of the doctrine was prevalent among these countries due to Japan's past of not delivering its promises. Additionally, the fact that Japanese visible trade surplus for July was as much as US$2.05 billion added to the extant feeling of suspicion. The reaction gradually turned inimical, which could be perceived to be Japanese ‘foot dragging’. There was caution, for example on Japanese credibility, with no aid to ASEAN being made. China's reaction, on the other hand, was