The Cambodia-Thailand Border Dispute under the 2026 Philippine Chairmanship
IMAGE: The ASEAN Foreign Minister’s Retreat in Cebu, Philippines on January 29. Supplied
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As the Philippines assumed the rotating chairmanship of the Association of Southeast Asian Nations (ASEAN), the regional bloc finds itself contending with a landscape defined by both ambitious economic integration and deep-seated security challenges.
While much of the international spotlight has focused on the crisis in Myanmar and maritime tensions in the South China Sea, the fragile peace along the border between Cambodia and Thailand has emerged as a critical litmus test for the new chair’s leadership.
Chaired by Philippine Secretary of Foreign Affairs Theresa Lazaro, the ASEAN Foreign Ministers’ Meeting (AMM) was the first major diplomatic gathering of the year in Cebu City underscored a core reality: the region continues to witness unresolved border concerns that threaten collective stability.
The current state of relations between Bangkok and Phnom Penh is characterized by a highly fragile ceasefire that was reached on December 27, 2025, following a year of devastating violence. Throughout the latter half of 2025, the border dispute escalated into major armed clashes in July and December, resulting in the loss of more than one hundred lives and the displacement of nearly a million people on both sides.
This resurgence of conflict, rooted in colonial-era treaties and competing claims over ancient temple sites such as Preah Vihear, pushed bilateral relations to their lowest point in decades. Despite the signing of a formal cessation of hostilities, the situation remains precarious. At the Cebu retreat, the Cambodian delegation presented evidence asserting that more than a dozen parts of Cambodian territory remain under Thai military occupation.
Cambodia’s claims of ongoing infringement were supported by reports of active Thai military operations even after the December agreement. Evidence shared during the high-level talks included observations of Thai forces digging new trenches and preparing fortifications in strategic areas close to the Preah Vihear Temple. Furthermore, the Cambodian delegation referred to observations made by the ASEAN Observer Team (AOT), which reportedly visited six different sites along the border and identified physical damage attributed to Thai military actions.
In response to these developments, Cambodia has lodged formal protests over what it describes as the illegal occupation of civilian areas and the destruction of infrastructure, characterising these acts as serious violations of international humanitarian law.
The Philippine chairmanship faces the difficult task of shepherding these two members toward a permanent resolution while managing a heavy broader regional agenda. During the AFMM Retreat, foreign ministers emphasised the central role of the AOT as the primary mechanism for monitoring and maintaining the peace. A significant administrative transition occurred as the Philippines officially took over the coordinator role for the team from Malaysia, which had facilitated the initial de-escalation efforts alongside other international actors. The mandate for these observers has been extended to ensure a continuous presence on the ground, tasked with verifying the implementation of the ceasefire agreement and preventing miscalculations that could lead to a return to open warfare.
However, diplomatic progress remains hindered by a profound lack of strategic trust between the two neighbours. A three-day meeting of the Regional Border Committee (RBC) secretariat, held at the Poipet International Border Checkpoint in late January 2026, concluded without reaching any consensus on key sticking points. While military representatives from both nations agreed to continue exchanging documents and maintaining communication channels, the failure to sign a formal agreement highlights the depth of the impasse. Thai officials have emphasised that turning to dialogue is a positive step but have warned that sustainable security cannot be achieved merely through documents on paper without true understanding and the cessation of provocative actions.
Recent technical and rhetorical incidents have further strained the peace. In early January, a Thai soldier was injured in an incident that Cambodia later attributed to an accidental discharge during cleaning activities rather than an intentional military strike. While Cambodia expressed regret for the injury, the incident led to formal protests and calls for stricter adherence to the joint ceasefire statement. Simultaneously, Thailand has cautioned its neighbour against remarks that could be interpreted as interference in its internal affairs, particularly regarding upcoming political transitions, stressing that sensitivity in language is essential to avoid misunderstandings.
The Philippine chairmanship must now navigate these internal divisions while attempting to project a unified regional front.
Secretary Lazaro expressed disappointment during the Cebu retreat that the severity of the border conflict had been overshadowed in public discourse by other regional flashpoints, noting that the gravity of a conflict claiming so many lives deserves sustained attention.
As the bloc moves toward the summits scheduled for later in the year, the effectiveness of the Philippine “Navigating Our Future, Together” theme will depend heavily on its ability to move the Cambodia-Thailand dispute from a monitored ceasefire to a sustainable, rules-based settlement. For ASEAN, the stakes involve not only the lives of those in the border regions but also the very credibility of the organization’s ability to manage conflict within its own family.
Seng Vanly is an independent geopolitical analyst. The views and opinions expressed are his own.
-Phnom Penh Post-
