Ecological Governance in the Mekong: U.S. Engagement and ASEAN’s Role amid Strategic Rivalry with China

The Mekong River, sustaining over 60 million people across mainland Southeast Asia, has emerged as a critical arena where transboundary water governance, environmental sustainability, and great power competition converge. As China consolidates its upstream influence through the Belt and Road Initiative (BRI) and the Mekong–Lancang Cooperation (MLC)—reshaping downstream hydrological conditions through an extensive Lancang dam cascade and deepening structural dependencies among smaller riparian states—the United States has recalibrated its engagement through the Mekong–U.S. Partnership (MUSP), emphasizing transparency, environmental standards, and multilateral cooperation as a strategic counterweight. ASEAN, as the region’s principal multilateral institution, must navigate this intensifying rivalry while confronting the ecological deterioration of a basin whose fisheries, agricultural systems, and community livelihoods face compounding pressure from hydropower development and climate change. This paper examines how major powers have adjusted their Mekong strategies since 2016, analyzes the environmental consequences of those adjustments through the water–energy–food–environment (WEFE) nexus and socio-hydrology frameworks, and assesses the Association of Southeast Asian Nations (ASEAN)’s institutional capacity to embed sustainability into basin governance. Drawing on a qualitative and comparative research design, the study situates the Mekong alongside the Nile, Danube, Indus, and Amazon basins to identify transferable governance mechanisms. The findings reveal that while ASEAN possesses meaningful institutional frameworks, its collective action capacity remains constrained by internal member-state divergences and its non-interference principle. The study concludes that incremental, technically grounded governance reforms pursued through ASEAN’s convening role represent the most realistic pathway toward a more sustainable and cooperative Mekong governance architecture.