The roots of the conflict extend back to the late 19th and early 20th centuries, marked by overlapping colonial claims and the legacy of unequal treaties. The 1960 Treaty of Peace and Friendship between Thailand and Cambodia, while intended to foster cooperation, failed to definitively resolve the maritime boundary issue, leaving it a persistent source of friction. The 2011 Permanent Court of Arbitration ruling, which largely favored Cambodia’s claims, further inflamed tensions and triggered violent clashes in 2014, resulting in significant casualties on both sides. Key stakeholders include Thailand, Cambodia, ASEAN, China (increasingly involved through economic leverage and strategic partnerships), and the European Union, which has expressed concerns about the impact on trade and regional stability. Thailand’s primary motivation is maintaining sovereignty and control over its maritime resources; Cambodia seeks to assert its territorial claims and secure economic benefits; ASEAN aims to mediate and prevent further escalation, often hampered by the reluctance of member states to openly confront each other.
“The core of the issue isn’t just about oil and gas; it’s about a fundamental denial of Cambodia’s historical rights and the broader signals it sends about the rules-based international order,” explains Dr. Amelia Stone, a Senior Fellow specializing in Southeast Asia Security at the International Institute for Strategic Studies (IISS). Recent developments over the past six months reveal an intensification of the conflict. In November 2025, Thai forces conducted a preemptive operation, dubbed “Operation Sea Shield,” resulting in a confrontation with Cambodian forces near the Koh Tru archipelago. Subsequently, Cambodian forces seized the Koh Rong Sanh islet, prompting a diplomatic crisis and triggering renewed calls for international arbitration. Satellite imagery analysis indicates an increase in naval deployments by both countries in the disputed zone. Furthermore, the ASEAN Special Ministerial Meeting scheduled for December 22nd, 2025, represents a crucial opportunity—or perhaps a point of further deadlock—for facilitating a resolution.
Data from the World Bank indicates a significant decline in investment in the Gulf of Thailand’s petroleum sector over the last decade, largely due to the uncertainty surrounding the maritime boundary. A 2023 study by the Center for Strategic and International Studies (CSIS) highlighted that “the unresolved dispute represents a potential disruption to over $200 billion in annual trade flowing through the Strait of Malacca.” The situation is further complicated by China’s growing economic and strategic influence in the region. China has become a key investor in Cambodia’s infrastructure projects and has quietly provided naval support to Phnom Penh, ostensibly to “protect” Cambodian fishermen.
Looking ahead, the next six months will likely see continued tensions and intermittent clashes, driven by nationalist sentiment and the competing strategic interests of the involved parties. A prolonged stalemate could lead to a wider regional crisis, particularly if China leverages the situation to advance its own interests. Longer-term, the potential for escalation remains a significant concern. Predictably, the outcomes within the next 5-10 years are marked by several potential paths. A hardline approach by either Thailand or Cambodia could trigger a protracted armed conflict, destabilizing the entire region. A more likely, albeit less desirable, scenario involves continued diplomatic maneuvering, punctuated by periodic confrontations, with ASEAN acting as a largely ineffective mediator. A successful, though improbable, outcome would involve a legally binding resolution of the maritime boundary issue, achieved through a comprehensive negotiation process facilitated by an impartial international body – a process heavily reliant on the willingness of all parties to compromise.
“The Gulf of Thailand’s maritime dispute is a microcosm of broader geopolitical trends – a clash between national sovereignty and international law, between regional power dynamics and global influence,” states Dr. David Miller, Director of the Southeast Asia Studies Program at the National University of Singapore. “The EU’s engagement, while focused on cybercrime, highlights the realization that these localized conflicts have far-reaching implications for the broader rules-based international order.”
The situation compels a fundamental reflection: the unresolved tensions in the Gulf of Thailand serve as a stark reminder of the fragility of regional stability and the imperative for proactive diplomacy and a renewed commitment to multilateralism. The question is not simply about resolving a territorial dispute; it’s about safeguarding the future of Southeast Asia’s economic prosperity and security.