Chapter 8 analyzes East Asian regionalism projects, which demonstrate that the choices of governments and non-state actors constitute the structure of East Asian international relations, albeit within evolutionary constraints. East Asian countries are not integrating in a European Union sense, but their desire for and efforts at regional cooperation remain strong. East Asian regionalism was underdeveloped compared to Europe and some other developing regions, but an economic regionalism open to non-East Asian countries emerged when the Cold War ended. The 1997 Asian Financial Crisis trigged greater East Asian efforts at creating more exclusive economic and financial groups, but East Asia has shifted to mega regionalism since the early 2010s, reflecting growing great power rivalries between Japan, China, and the United States. Other East Asian countries, particularly those in the Association of Southeast Asian Nations (ASEAN), have their own agency and drive the process in more immediate terms.

This chapter charts developments in Southeast Asia concerning regional economic integration through the conclusion of plurilateral trade and investment agreements.It examines the early steps towards achieving economic integration, including the creation of the Association of Southeast Asian Nations (“ASEAN”) in 1967, and the progressive steps that Southeast Asian States have taken to liberalise their economic and investment policies through the ASEAN framework.It then considers various recent and ongoing developments in regional economic integration, including the negotiation of the Trans-Pacific Partnership Agreement and its revival as the Comprehensive and Progressive Agreement on Trans-Pacific Partnership, the creation of the ASEAN Economic Community, and the ongoing negotiation of the Regional Comprehensive Partnership Agreement.It concludes with the observation that many innovations in the negotiation of IIAs are emerging from the practice of ASEAN and other Asian States which are having broader implications on the field of international investment law.