Background
The Cambodia-Thailand Joint Commission on Demarcation for Land Boundary (JBC) is the bilateral mechanism charged with coordinating on-the-ground surveys and the emplacement of temporary boundary markers under existing bilateral agreements and joint statements.
The Ministry of National Defence reported that, after the JBC special meeting in Chanthaburi on 22 October 2025, implementation of joint survey and temporary emplacement by Joint Survey Teams (JSTs) was halted at Chouk Chey village, Prey Chan village, and along the boundary segment between pillars 52–59 due to operations by Thai security forces, according to the ministry briefing to ASEAN observers on 27 July 2026. The ministry also cited the Royal Government of Cambodia’s invocation of historical delimitation instruments and agreements—including the Frenco‑Siamese conventions, the MOU 2000, and the TOR 2003—when rejecting any alteration of the international boundary resulting from the use of force.
Key Developments
On 27 July 2026 in Siem Reap province, the Coordination Liaison Group (CLG) of Cambodia facilitated a briefing for the ASEAN Observer Team–Cambodia (AOT-KH) led by Commodore Glenn Z. Dizon. The briefing was delivered by Mr. Promsoeun Wattanak, head of the Cambodia-Thailand Joint Survey Team within the State Secretariat of Border Affairs, and focused on the progress of demarcation and temporary marker emplacement between Cambodia and Thailand.
The Ministry’s statement says joint survey and emplacement activities by JSTs were completely disrupted and remain stalled at specified sites, and that Cambodia has issued multiple formal diplomatic notes of protest regarding the alleged occupation and actions by Thai forces along parts of the boundary.
Institutional Role
The Coordination Liaison Group (CLG) of the Kingdom of Cambodia is the domestic facilitator that arranged the presentation and engagement with ASEAN observers; the AOT-KH participates in-country as an observer to confidence-building activities. The State Secretariat of Border Affairs provides technical representation within JSTs and reports on implementation progress of JBC-mandated tasks.
Implications for Bilateral Process
The Defence Ministry reiterated Cambodia’s request that the Thai side dispatch Joint Survey Teams to resume on-the-ground survey and emplacement, and called for prompt convening of JBC and related technical meetings in accordance with previously agreed minutes and joint statements (including references to the GBC joint statement of 27 December 2025 and the JBC agreed minutes of 22 October 2025). The ministry emphasised continued formal diplomatic protest against actions it describes as unilateral changes to the boundary line effected by force.
