Prime Minister Anutin Charnvirakul committed Thailand on June 5 to the UNCLOS maritime conciliation Cambodia had triggered three days earlier, and in the same statement closed every other channel and questioned the legitimacy of Cambodia’s move to take the dispute abroad. Thailand will appoint two conciliators, with Deputy Prime Minister and Foreign Minister Sihasak Phuangketkeow leading its side. Everything else stays frozen.
Cambodia instituted the compulsory conciliation on June 2, notifying Thailand and the United Nations secretary-general under the UN Convention on the Law of the Sea, after the Thai cabinet moved on May 5 to cancel the 2001 memorandum of understanding that had framed a quarter-century of stalled talks over the overlapping claims. Prime Minister Hun Manet, announcing the step, said Cambodia had “no alternative but to initiate compulsory conciliation proceedings under UNCLOS” once that framework was gone.
What Anutin agreed to enter has procedural force. Conciliation was the route left open after both governments had ruled out compulsory binding adjudication for sea-boundary delimitation, and after Thailand cancelled the framework Cambodia had treated as the remaining avenue for negotiation. Thailand declared in 2011, and Cambodia in its 2026 declaration on ratification, that it would not accept the binding courts or arbitration in Part XV for disputes over sea-boundary delimitation. Article 298 lets a state carve those disputes out of compulsory adjudication. What the same provision does not let it do is escape conciliation. A state that has made the carve-out must, under Article 298(1)(a)(i), accept compulsory conciliation at the other party’s request when negotiations have not produced agreement within a reasonable period. Cambodia made the request, and Thailand must appoint and contest scope. The commission’s report, Annex V states, “shall not be binding upon the parties.”
What the report cannot do is bind, and that pushes the contest past whether the forum applies and onto what the panel may do once it sits. Under Annex V Article 13, “[a] disagreement as to whether a conciliation commission acting under this section has competence shall be decided by the commission.” The body rules on its own reach before any boundary, and two arguments give Thailand something to put to it.
Compulsory conciliation reaches a delimitation dispute only where it “arises subsequent to the entry into force of this Convention.” In the only prior compulsory conciliation the convention has produced, between Timor-Leste and Australia, the commission read that phrase as the convention’s general entry into force on 16 November 1994, not the date it bound those two parties. Cambodia’s claim line in the gulf dates to a decree of 1 January 1972, and Thailand answered with its own 1973 continental-shelf declaration. Thailand can argue that a dispute rooted in claim lines drawn before that cutoff falls outside the commission’s reach.
Article 298(1)(a)(i) also shields land from a maritime panel, excluding “any dispute that necessarily involves the concurrent consideration of any unsettled dispute concerning sovereignty or other rights over continental or insular land territory.” Thailand can point to Koh Kut, which it treats as settled under the 1907 Franco-Siamese treaty and which is crossed by Cambodia’s 1972 line. If the boundary cannot be fixed without first deciding who owns the island, the dispute is one the commission may not hear. Cambodia can answer both: that the live dispute is the failure to settle the boundary after the 2026 cancellation, not only the age of the claim lines; and that Thailand would still have to show that fixing the boundary necessarily requires deciding an unsettled land-sovereignty question.
Cambodia has pushed the other way, asking the panel to take in more than the boundary. It proposed that the conciliation cover joint development of the area’s resources even if agreement on the boundary itself fails. Thailand rejects the addition, arguing that conciliation is confined to delimitation and that any resource-sharing would require a separate agreement reached first. Whether interim benefit-sharing belongs inside a delimitation conciliation is, again, for the commission. In asking for it, Cambodia reads the instrument broadly, and a panel measuring its own competence may read it more narrowly.
Anutin’s commitment came with a refusal and a charge. Asked whether Cambodia had again seized the initiative abroad, he said “those who have to run here and there are the ones trying to seek legitimacy … Because there is illegitimacy involved.” He ruled out every other channel while the process runs, with no restoration of relations, no reopening of border crossings, no Joint Boundary Commission and no General Border Committee, and all border gates to stay shut. The freeze sits against Sihasak’s argument the same week that the two sides should have tried bilateral talks first: Thailand pressed for talks, then suspended the channels that would carry them. Cambodian Foreign Minister Prak Sokhonn said Cambodia “hopes that the Thai government will engage with this process in good faith.”
Sihasak rejected the idea that Thailand had been “dragged” into the mechanism: a party can decline to take part, but the proceedings continue without it, with conciliators named on the absent side’s behalf. That point is the convention’s, not Bangkok’s. Annex V provides that a failure to submit “shall not constitute a bar to the proceedings.”
Thailand also took the dispute outward, with Sihasak briefing 67 ambassadors and the foreign ministry issuing a seven-point position for direct talks. He had wanted six months of talks before any conciliation, voluntary or compulsory, he told Reuters. He also said Cambodia had gone public before notifying Thailand, and that the two governments had not spoken since June 2; a Cambodian government spokesperson rejected that account, showing Reuters images of a timestamped email and paper notice delivered Tuesday morning that Reuters could not confirm. Prak Sokhonn said Thailand had three weeks to respond to the notification.
The zone covers about 26,000 square kilometres of the Gulf of Thailand, with reserves put at nearly 12 trillion cubic feet of gas and oil and an often-cited value near $300 billion, an estimate, not a surveyed total. Cambodia, which signed the convention in 1983 but ratified only this year, casts that step as securing its legal footing.
The Timor-Leste conciliation is the measure of what comes next. It ran close to two years, the commission settled its competence over Australia’s objections as a first order of business, and its non-binding report became the basis for the boundary treaty the two states negotiated afterward. Sihasak cited that case in declining to estimate a timeline. Thailand has 21 days to name two conciliators, the response window Prak Sokhonn set out; Cambodia has chosen its pair, and Thailand has selected two with backgrounds in international law pending cabinet approval; the four then choose a fifth as chair, perhaps within a month. Before any of them weighs a boundary, they will weigh the precedent both governments will cite, which read entry into force as 1994 and would now be turned on claims first drawn in 1972 and 1973.Share