Cambodia-Thailand Border and Maritime Disputes: Diplomacy and Boundary Negotiations

Cambodia reaffirmed its commitment to raise the bilateral border dispute with Thailand at the Francophonie summit in Phnom Penh on September 3, 2026. Thailand conceded Cambodia's right to voice the issue but maintained its position on the sovereignty of its own claims, insisting that international forums cannot determine territorial boundaries. The dispute remained unresolved as both nations continued to assert their respective positions. Thailand initiated its first United Nations Convention on the Law of the Sea (UNCLOS) conciliation process with Cambodia on September 13, 2026. The United Nations commenced a formal hearing on the Thai-Cambodian sea border dispute on September 14, 2026. These steps marked a significant diplomatic shift toward resolving maritime boundaries in the Gulf of Thailand through formal international mechanisms. Cambodia and Thailand began the first meeting of the UNCLOS Compulsory Conciliation Commission in Singapore on September 15, 2026. Cambodia informed the commission of its intent to negotiate a comprehensive maritime boundary treaty and submitted three proposed resolutions. Cambodia challenged Thailand to focus on legal and practical solutions rather than unrelated accusations. Thailand's Foreign Minister Sihasak Phuangketkeow accused Cambodia of spreading false narratives and unfounded accusations against Thailand during the proceedings. Thailand adopted a combative stance during the UNCLOS session held from September 14 to 16, 2026. Thailand mixed maritime and land boundary issues and accused Cambodia of 'playing the victim'. Cambodia expressed readiness for the next step in the compulsory conciliation process despite the fiery nature of the session. The proceedings were expected to influence regional stability and compliance with the December 27, 2025 ceasefire agreement. Cambodia's Foreign Minister Prak Sokhonn addressed the UN General Assembly on September 26, 2026, urging Thailand to implement border agreements, resume demarcation work, and allow over 20,000 displaced Cambodian civilians to return home. Cambodia defended its decision to seek international conciliation following criticism from Thailand’s Prime Minister at the UN. On September 29, 2026, Thai diplomat Cherdchai Chaivaivid addressed the UN General Assembly, urging Cambodia to avoid discussing border issues at international forums. He claimed Thailand respected the December 27, 2025 ceasefire, despite reports of 20,000 Cambodian civilians remaining displaced due to Thailand’s occupation of Cambodian territory.