Thai Deputy Prime Minister and Minister of Foreign Affairs Sihasak Phuangketkeow met his Cambodian counterpart, Deputy Prime Minister and Minister of Foreign Affairs and International Cooperation Prak Sokhonn, at United Nations headquarters in New York on 26 May, on the sidelines of a Security Council open debate, and the two governments reached no agreement on a framework for negotiating their maritime boundary, Sihasak said afterward. It was the first direct ministerial contact since Prime Minister Anutin Charnvirakul met Prime Minister Hun Manet at the ASEAN summit in Cebu earlier in the month.
The meeting closed a sequence that began three weeks before it. On 5 May the Thai cabinet terminated the 2001 maritime Memorandum of Understanding, the agreement known as MoU 44 that had stood for more than two decades as the only bilateral framework for the two countries’ overlapping claims in the Gulf of Thailand. Within hours Prak Sokhonn announced that Cambodia would move to compulsory conciliation under the UN Convention on the Law of the Sea. “Today, following Thailand’s unilateral rejection of MoU-2001, Cambodia announces that it will initiate compulsory conciliation with Thailand under the UN Convention on the Law of the Sea,” he said. The foreign ministry said Cambodia had “no option” but to trigger the mechanism.
At stake is the Overlapping Claims Area, roughly 26,000 square kilometres of Gulf seabed believed to hold significant oil and gas. MoU 44, signed in Phnom Penh in 2001, had paired boundary delimitation with joint development of those resources in a single package. Prak Sokhonn described it as “the only bilateral framework between our two countries for addressing overlapping maritime claims and pursuing maritime boundary delimitation peacefully and in accordance with international law,” and said its termination “does not affect Cambodia’s lawful rights over its maritime areas.”
The cancellation changed which legal doors stood open. Both states, on joining UNCLOS, excluded sea-boundary delimitation from the convention’s binding procedures under Article 298, shutting off the International Tribunal for the Law of the Sea, the International Court of Justice and Annex VII arbitration as routes to a binding decision on the boundary itself. The same article carries a proviso: a state that lodges the exclusion must still accept compulsory conciliation under Annex V when a dispute arises after the convention entered into force for it and negotiations have not reached agreement within a reasonable time. Conciliation produces a report, not a binding ruling. The procedure has run once between states, in the Timor-Leste and Australia case the Permanent Court of Arbitration administered from 2016, and the facts there differ from the Gulf of Thailand.
Thailand’s answer since the vote has been to ask for the bilateral talks the cancelled instrument used to house. Sihasak rejected reports that Bangkok had agreed to conciliation and put direct negotiation ahead of any convention route. “The most appropriate starting point was for Thailand and Cambodia to negotiate directly and exhaust bilateral talks before considering other mechanisms under the convention,” he said. Conciliation could not proceed unless both sides agreed to it, he added, and would yield recommendations rather than binding decisions. His prime minister read the same cancellation differently. Anutin said the two countries would “now be operating under the same set of rules,” that “whatever discussions take place from now on, new rules and frameworks must be agreed upon together,” and that his own account of the Cebu meeting counted as notice: “For me, informing Cambodia of Thailand’s withdrawal from MoU 44 during this meeting can clearly be regarded as official notification.”
Hun Manet put the sequence on Thailand. “It is regretful that Thailand has decided to unilaterally withdraw from this MoU, while Cambodia has consistently prioritised bilateral mechanisms in line with this MoU,” he said, adding that Cambodia now had “no choice but to rely on international law.” Phnom Penh carried that line into New York. Prak Sokhonn reaffirmed compulsory conciliation as a peaceful and lawful route to the boundary question and called for full and good-faith implementation of the Joint Statement of 27 December 2025, the document Cambodia treats as the standing framework for stability along the frontier. He told Sihasak that Cambodia remained ready to work with Thailand on the confidence-building steps the two prime ministers had set out in Cebu.
The conciliation route is bounded. The proviso opens it only for disputes arising after the convention entered into force and only where negotiation has failed within a reasonable time, and a commission’s report binds neither party. Sihasak’s position puts the bilateral track first. Prak Sokhonn’s reading treats the cancellation of the only bilateral framework as the negotiation failure that opens the convention’s door. The 26 May meeting did not resolve which reading governs, and both ministers agreed to keep communicating.