1. Development of regionalism after the Cold War

　The 30 years following the end of the Cold War are coincidentally almost the same as the Heisei period. During this period, the international environment in Asia changed drastically. One of these is the development of regionalism in Asia. During the Cold War, Asia was said to be a region lacking regionalism. Moreover, it was believed that cooperation could only be expected in a limited range of areas that included economic, social and cultural cooperation due to both the Cold War between the United States and the Soviet Union and the Sino-Soviet confrontation. That had deep impacts and induced complicated political confrontation.
　This situation began to change thanks to some moves toward regional integration in North America and Europe, which led to the establishment of European Community (EC) and the conclusion of NAFTA. In November 1989, the Asia-Pacific Economic Cooperation (APEC) was launched as an intergovernmental organization of economic issues. Also, the possibility of all-out nuclear war through direct confrontation between the United States and the Soviet Union faded into the background because of the end of the Cold War. Instead, the threat of nontraditional security issues, such as local and ethnic conflicts, civil wars, terrorism, and transnational crimes called for the need for security and political cooperation under new circumstances. As a result, the ASEAN Regional Forum (ARF) was established in 1994.
　Subsequently, ASEAN+3, which began in 1997, was rapidly institutionalized as a framework for East Asian regional cooperation in the economic, political and security areas due to the Asian Financial Crisis that just broke out in the summer of the same year. It operates within a concrete framework, including monetary and financial cooperation such as the Chiang Mai Initiative (CMI) and food security cooperation such as the ASEAN+3 Emergency Rice Reserve (APTEER). Furthermore, the East Asia Summit (EAS) was founded in 2005 at a time when discussions on the establishment of an East Asia Community were heating up. In addition to ASEAN countries, eight major countries in the Asia-Pacific region, including Japan, China, the United States, and Russia, function as a forum for discussing regional issues. Also, ADMM Plus, a meeting of defense ministers from the same countries as the EAS, was launched in 2010. ASEAN itself, the core of these institutions, advance their integration. In 2015 declared the establishment of the ASEAN Community (AC), which consists of the three pillars of a security community, economic community, and social and cultural community.
　On the other hand, regional cooperation initiatives emerged outside East Asia, such as the Indian-Ocean Rim Association (IORA), Bay of Bengal Initiative for Multi-Sectoral Technical and Economic Cooperation (BIMSTEC), and the Shanghai Cooperation Organization (SCO) that originates in the Shanghai 5, led by China and Russia along with the Central Asian countries. Under Prime Minister Thaksin Shinawatra, Thailand independently promoted proactive diplomacy, establishing the Thailand-led regional frameworks such as the Asia Cooperation Dialogue (ACD) and Ayeyawady-Chao Phraya-Mekong Economic Cooperation Strategy (ACMECS).
　It is clear that Asian regionalism has rapidly developed over the past 20 years or so since the end of the Cold War. This is also part of the rise of regionalism worldwide which was driven by the prevalence of the view that sees it right to deal with various problems through international cooperation and to institutionalize such efforts under the liberal international order supported by U.S. hegemony after the Cold War. Under this liberal international order, the movement toward regional economic cooperation and integration accelerated among countries that adopted a liberal economy based on market principles and believed that deeper penetration of globalization would lead to their own growth.

2. Current Status of Asian Regional Cooperation and Japan's Diplomacy in Asia (As of 2019)

　Besides its traditional bilateral diplomacy, Japan has been actively involved in the development of such regionalism and has played a major role. As of 2019, regional institutions and regionalism are becoming increasingly important diplomatic tools for Japan and other countries as a means of responding to uncertain international situations.
　Underlying the uncertain international situation is the instability of the liberal international order led by the United States. This concern was already shared among some observers after the unilateralism of the Bush administration as exemplified by the Iraq war. Furthermore, the global economic crisis triggered by Lehman Brothers' collapse in 2008 further shook the liberal international order centering on U.S. hegemony and the liberal economy. The process of addressing the crisis spotlighted the rise of emerging economies such as China and India.
　In the 2010s, China's political and economic presence increased unprecedentedly. China started actively formulating foreign policy related to the construction of regional and international orders, such as the proposal for the Belt and Road Initiative and the Asian Infrastructure Investment Bank (AIIB). Furthermore, since the inauguration in January 2017, the Trump administration has come up with a policy of antagonizing China as a "Revisionist Power" and aiming for "decoupling". The trade "war" with China, which opposes this policy, has escalated.
　Ironically, regionalism has become more active in these uncertain circumstances. This is because Japan and other countries have used regionalism and regional systems as a tool to secure their own interests and build a regional order that is desirable for them in these uncertain times. The Trans-Pacific Partnership (TPP), signed in 2016 under a strong American leadership and centripetal force, was imperiled by the Trump administration withdrawing from the agreement in 2017. However, Japan, Singapore, and other countries took initiatives to conclude the "Comprehensive and Progressive Trans-Pacific Partnership (CPTPP)," which entered into force in 2018, without the participation of the United States. The Comprehensive Economic Partnership in East Asia (RCEP), a framework launched in 2012 by sixteen countries--ASEAN, Japan, China and Australia--continues to this day, albeit with difficulty in negotiations, and is making progress toward its conclusion by the end of 2020. While ASEAN declared the establishment of the ASEAN Community at the end of 2015. , the chairman's statement at the ASEAN Summit and the ASEAN Ministerial Meeting has come to attract attention every time as an indicator of the future of the South China Sea issues. Regioal forums, including ASEAN Summit, the EAS, and the ADMM Plus, becomes a venue for candid exchanges of views related to security issues such as the South China Sea (There are some cases that where discussions heat up)
　Japan and the United States have proposed the concept of a "Free and Open Indo-Pacific (FOIP)". The FOIP calls for Japan to link the two continents of Asia and Africa as well as the two oceans, the Pacific and Indian Oceans, and to realize peace and prosperity in the Indo-Pacific region through the dynamism created by the linkages. The three pillars of this cooperation are: (1) Promotion and establishment of the rule of law, freedom of navigation, free trade; (2) the pursuit of economic prosperity by improving physical, and people-to-people, and institutional connectivity, especially high-quality infrastructure; and (3) the assurance of peace and stability through capacity building assistance and cooperation in the fields of humanitarian assistance and disaster relief.
　

3. Japan's Regional Diplomacy

　For Japan, which is no longer the "sole economic power" or the "only developed country" or "a special country" in Asia, the establishment of a desirable regional order and environment through the utilization of regional systems is becoming increasingly important. For the time being, it is best for Japan to choose hedging against the present uncertainty by adopting a multidirectional regionalism strategy, such as strengthening its relations with ASEAN, engaging in ASEAN-centered regional institutions, promoting regional economic integration through the CPTPP and RCEP, and concretizing the contents of the FOIP Vision. In the long term, it is necessary to further promote concrete cooperation with neighboring countries in Asia for the realization of such a vision by tackling daunting questions, such as how to achieve sustainable economic prosperity, how to stabilize regional security environment as the foundation of prosperity, and what political system and what kind of society the people of Japan and other countries should live in the future. As confrontation of interests is and will be common in the international community, regional multilateralism is significant for maintaining the peaceful coexistence of multiple diverse actors in the world.
But now, the coronavirus pandemic casts a shadow on the prospect of regional multilateralism in Asia. Many countries have now imposed travel restrictions and are trying to close their own borders instead of promotion of international cooperation to fight against the pandemic. These trends heavily have negative impact on the global supply chains fostering economic development and independence in Asia and might be the serious challenges against regional multilateralism. However, in these difficult situations, regional multilateralism should be kept and developed by Japan and other countries in Asia for stability and prosperity in the region.