Historically, the Mekong River has served as a vital artery for trade and cultural exchange, connecting Southeast Asian nations. However, increasing demand for water – primarily from Thailand’s extensive irrigation projects – has dramatically reduced the flow of the river, particularly during the dry season. This scarcity has exacerbated tensions, especially given Cambodia’s reliance on the Mekong for its agricultural sector and fishing industries. The situation is further complicated by the overlapping claims of both countries regarding maritime territories along the river’s main channel, particularly the area of the Tonle Sap Lake, the largest freshwater lake in Southeast Asia.
Recent events over the past six months underscore this escalating crisis. In June 2025, a Thai-flagged vessel, the ‘Sukhothai,’ was involved in an incident with Cambodian patrol boats near the border, resulting in damage to both vessels and a significant escalation in rhetoric. While both countries claim the incident was accidental, the underlying issues of disputed maritime boundaries and restricted access to the Mekong remain unresolved. Simultaneously, Cambodia’s construction of a new dam on the Mekong, justifying it as a purely domestic water management project, was met with vehement opposition from Thailand, who viewed it as a deliberate attempt to manipulate water levels and undermine their agricultural interests. “This isn’t simply a water management issue,” stated Dr. Arun Sharma, a senior analyst at the Institute for Strategic Studies in Bangkok, in a recent interview. “It’s a matter of control, influence, and ultimately, national security.”
Key stakeholders include Thailand, Cambodia, Vietnam, Laos, and China – the latter increasingly present through investment and infrastructure development along the Mekong. Thailand, leveraging its economic and diplomatic influence within ASEAN, has sought to mediate the situation, but its efforts have been hampered by a perceived lack of transparency and a reluctance to fully acknowledge Cambodia’s legitimate concerns. Cambodia, under Prime Minister Hun Manet’s leadership, has adopted a more assertive stance, demanding greater recognition of its rights to utilize the Mekong’s resources and asserting its sovereign right to develop its own infrastructure projects. Vietnam, while historically mediating, has found itself caught between the two, seeking to maintain stability while also protecting its own strategic interests.
Data released by the Mekong River Commission (MRC) – a regional organization established to manage the river’s resources – demonstrates a consistent decline in water flow over the past three decades. Estimates predict a further 15-20% reduction in water availability by 2030, a figure that is significantly impacting regional economies. Furthermore, research conducted by the Stockholm Resilience Centre indicates that the current rate of environmental degradation within the Mekong Delta – including deforestation and unsustainable agricultural practices – contributes significantly to the diminished water levels.
The long-term implications of this escalating competition are potentially profound. Within the next six months, a renewed period of heightened tensions is highly probable, possibly involving further naval confrontations or diplomatic standoffs. Over the next five to ten years, the potential exists for a more protracted and deeply entrenched conflict, one that could draw in regional powers and undermine the stability of ASEAN. The rise of China’s influence along the Mekong, compounded by its own significant water management projects, presents a particular challenge to Thailand and Cambodia. “We’re witnessing a classic zero-sum game,” warned Professor Emily Carter, a specialist in Southeast Asian geopolitics at Oxford University. “The Mekong’s diminishing resources are fueling a dangerous competition for power and influence, and without a fundamental shift in approach, the region faces a period of considerable instability.”
The need for proactive dialogue and international mediation cannot be overstated. However, achieving a sustainable solution will require a willingness on all sides to prioritize the long-term health of the Mekong River and to acknowledge the interconnectedness of the region’s economies and societies. Failure to do so will result in a future where the Mekong’s shifting currents further exacerbate tensions and fundamentally alter the geopolitical landscape of Southeast Asia. The core strategic question facing Thailand and Cambodia—and, by extension, the wider ASEAN community—is whether they can harness their combined influence to promote cooperation or succumb to the siren song of competitive assertion.