This book provides a valuable insight into the Mekong River subregion, which consists of China, Myanmar, Thailand, Laos, Cambodia, and Vietnam.It investigates numerous policy-relevant issues, including Mekong water governance, economic cooperation, and security affairs, while examining the role of global powers in the region, particularly the US, China, Japan, and South Korea, with their overlapping and conflicting strategies and policy priorities. Revealing how the competition between the US-led order and China-led order is evolving in mainland Southeast Asia and addressing the problems in the Mekong subregion, the book goes on to examine the Mekong subregional institutions and the role that they play in the policies of both the Mekong countries and the external powers.In exploring the increased involvement of major powers, including the US, China, Japan, South Korea, and Australia in the Mekong subregion, this book will be a valuable resource for students and scholars of Asian studies, comparative politics, and international relations.