The Ayeyawady-Chao Phraya-Mekong Economic Cooperation Strategy (ACMECS) was initially launched to narrow development gaps and complement ASEAN integration among the Mekong riparian states, including Thailand, Lao PDR, Myanmar, Cambodia, and Vietnam. Over two decades, ACMECS witnessed rapid regional economic growth, averaging 6-8% annually, and closer integration among its 230 million people. It also introduced the “3S” goals of Seamless Connectivity, Synchronized ACMECS, and Smart & Sustainable ACMECS as guiding pillars for a “Connected Mekong Community”. Concurrently, ACMECS clearly emphasizes that the building of a regional community also relies on a solid and comprehensive security foundation. Hence,
ACMECS today is not only a platform for connectivity and economic projects, but also a mechanism to jointly tackle transnational and cross-cutting issues in the Mekong subregion. Overall, the security challenges facing the subregion are predominantly non-traditional in nature, including water resources management, transboundary pollution, and transboundary crime. These riparian challenges are fundamentally “water-related” and, amid increasing water mobility and cross-border population movements, continue to spill over into other dimensions.
Water Resources Management
As with most international basins, increasingly trade-offs of water-resource development have emerged as a critical challenge for ACMECS. This tension is often described as a tripartite development dilemma of “urgent needs for hydropower, strong demand for agriculture, and heightened concerns about flooding risks.” Based on each country’s needs, over 700 dams have been constructed along the Mekong and its tributaries, serving diverse development purposes such as hydropower generation, irrigation, water supply, and
flood control. This “congestion of dams” also reflects the governance dilemma of insufficient coordination capacity for water resource management, data sharing, and environmental monitoring, which directly impacts the whole-basin water security and ecological balance. Simultaneously, riparian communities are experiencing more extreme hydrological swings due to climate change. For example, severe droughts in 2019-2020 caused Mekong River levels to plunge to record lows, disrupting livelihoods across the subregion. In 2023, Typhoon Yagi caused massive floods across the Mekong region, affecting over 5 million people and causing an estimated 16.6 billion dollars in damages.
Transboundary Pollution
Industrialization, while driving productivity and economic growth, often intensifies pollution. Rivers carry untreated wastewater, agricultural runoff containing pesticides, fertilizers, and mining by-products such as heavy metals from one point to the whole water system. Furthermore, because the Mekong River ultimately flows into the Pacific Ocean, pollution generated within the basin does not stop at the river itself but disperses into marine environments. As a result, pollution in the Mekong has become closely linked to the Pacific environmental challenge, extending beyond subregional boundaries and evolving into a broader regional and even global concern. One particular case is plastic waste pollution. The Mekong River is estimated to flush 22,800–59,900 tons of plastic debris into the Pacific Ocean each year, making it one of the world’s most polluted waterways by plastic. Plastics discarded on land or in waterways flow whole-streamly, break into microplastics, and eventually enter the food chain and marine environment.
Transboundary Crime
In the Mekong Basin, the mobility of water, the movement of people, and transboundary crime are not independent phenomena but form a mutually reinforcing cross-border chain. Hydrological changes impact riparian livelihoods and transport corridors, thereby driving cross-border population movement. Meanwhile, transnational criminal networks exploit uneven governance capacities along rivers and border areas to embed illicit activities within the spaces and networks of movement. Development deficits often constitute the starting point of this risk. When droughts, floods, or reservoir operations disrupt agricultural and fisheries incomes, some individuals are more likely to turn to high-risk migration or informal employment, increasing their vulnerability to fraud, exploitation, or involvement in illicit economies. Against the backdrop of relatively weak law enforcement and supervision, this vulnerability has gradually turned waterways and border crossings into high-frequency cross-border flow “corridors.” As a result, transnational crimes confronting ACMECS member states, including drug trafficking, human and wildlife trafficking, as well as online and financial fraud, are not isolated incidents but the cumulative outcome of long-standing regional development imbalances and governance disparities.
ACMECS’ Function
In the Mekong, the challenge landscape is shaped by a network of non-traditional security (NTS) issues centred on water resources. Vertically, these water-related issues spill over into other domains, including energy security, food security, ecological security, and human security. Horizontally, those challenges in the Mekong are intertwined with social, national, regional, and even global concerns. Therefore, effective governance of Mekong water resources lies at the core of building a “community with common security.”
A series of ACMECS documents has clearly articulated the framework’s commitment to institutionalising the governance of non-traditional challenges. A major milestone was the Hanoi Declaration adopted at the 7th ACMECS Summit in 2016, in which member states agreed to deepen cooperation on environmental issues.
The Declaration emphasised strengthening environmental conservation and the sustainable use of natural resources, coordinating efforts to advance the 2030 Sustainable Development Goals, and enhancing collaboration with the Mekong River Commission and other regional mechanisms to jointly and sustainably manage shared water resources.
At present, ACMECS demonstrates an advanced approach to governing NTS issues through the use of technology, data sharing and the integration of regional and international standards. These strengths have also been extended to the governance of transboundary pollution. The Master Plan (2019-2023) further operationalised the “Smart and Sustainable ACMECS” goal by prioritising capacity-building in integrated water resources management, technical support for sustainable basin-level decision-making, and developing the continuous monitoring network and monitoring mechanisms for transboundary pollution and water quality. At the 10th ACMECS Summit (Nov 2024), leaders “highlighted cooperation in Mekong water resources management” and agreed on measures such as real-time hydrological data sharing among all five countries and jointly developing an early warning system for natural disasters. The summit also endorsed a “Concept Note on Water Resources Management in the Mekong Sub-region,” providing guidelines to enhance strategic coordination on both short- and long-term water challenges. This is a notable milestone, as it institutionalises water and environment cooperation within ACMECS.
Finally, regarding the effort against transnational crimes, ACMECS explicitly lists transnational crimes among the “multi-dimensional challenges” confronting the sub-region. A notable milestone was Thailand’s proposal, welcomed at the 9th Summit, to add a new pillar called “Safe and Secured ACMECS” to the cooperation framework. In practice, ACMECS has bolstered dialogue and coordination among law enforcement agencies of the five countries in natural resource management. Meanwhile, to ensure the efficiency of implementing the law enforcement, ACMECS should be encouraged to collaborate with joint patrols and operations along the Mekong River, such as the Lancang-Mekong Integrated Law Enforcement and Security Cooperation Centre.
Moreover, in light of the interlinked dynamics of “hydrological shocks–livelihood vulnerability–transnational crime” within the basin, ACMECS should fully leverage its strengths in data sharing and partnership-building by integrating water security, human security, and joint law enforcement into a single risk assessment framework. By treating hydrological and livelihood data as early-warning indicators of crime risk, ACMECS can promote more anticipatory governance. Such a coordinated approach should extend beyond hydrological and pollution monitoring to include data sharing, cross-border cooperation, and joint enforcement related to population mobility, labour, fraud, and drug trafficking.
