Cambodia’s Minister of Mines and Energy, Keo Rottanak, told Reuters in an interview published on 28 May that pressure on global oil supplies from the conflict around the Strait of Hormuz had sharpened the case for developing the contested seabed in the Gulf of Thailand, and that the way to reach it now runs through compulsory conciliation under the UN Convention on the Law of the Sea. He valued the area’s resources at an estimated US$300 billion and said the conciliation route “is the only possible avenue to sort out differences in a peaceful and amicable manner.”
On 5 May, Thailand’s cabinet approved the termination of the 2001 Memorandum of Understanding, known in Thailand as MoU 44, that had governed the two countries’ overlapping maritime claims for 25 years. Prime Minister Anutin Charnvirakul said the cancellation was unrelated to any conflict and carried out his policy to end an agreement that had produced no progress. The government spokesperson said the step was meant to adjust the “cooperation framework” rather than end negotiations, that Thailand had “unofficially informed Cambodia” of the termination, and that it was preparing to use UNCLOS as the basis for the next round of bilateral talks.
The agreement Thailand ended carries no termination clause. Its operative text is five articles and a signature block, with no provision for withdrawal, denunciation, or expiry, and no clause setting out how disputes about the MoU itself are to be resolved. The text ties joint development and boundary delimitation together as, in its own words, “an indivisible package,” so the two could not be negotiated apart; ending the MoU closed the resource-sharing track and the delimitation track at once.
Thailand’s own foreign ministry had set out, eighteen months before the cancellation, why the instrument served Thai interests. In a statement carried by the government’s public relations department in November 2024, under the Pheu Thai-led government of Prime Minister Paetongtarn Shinawatra, Vice Minister for Foreign Affairs Russ Jalichandra called MoU 44 “Thailand’s most effective tool for protecting its interests in maritime boundary and resource-sharing negotiations,” said that cancelling it “would not eliminate Cambodia’s territorial claims,” and recounted that a 2009 cabinet resolution to cancel the agreement was reversed in 2014 after studies found its strategic advantages. The Bhumjaithai-led government that ended the agreement, under Anutin Charnvirakul, took office in September 2025.
Both states had already shut the binding routes. Thailand in 2011 and Cambodia in February 2026 each lodged declarations under Article 298 of UNCLOS that exclude sea-boundary delimitation, together with the convention’s other optional exceptions, from compulsory settlement. Neither can be compelled into binding adjudication over the boundary itself. What survives that exclusion is the conciliation proviso written into Article 298: a state that filed the declaration must accept compulsory conciliation under Annex V when another party asks for it. The proviso sets its own terms. The dispute has to postdate the convention’s entry into force, the two sides must have failed to reach agreement in negotiations, and the matter must not require deciding an unsettled dispute over land territory at the same time. A conciliation commission’s report is not binding.
While the MoU stood, Thailand had a further argument against conciliation. Article 298 excludes from compulsory conciliation any sea-boundary dispute “to be settled in accordance with a bilateral or multilateral agreement binding upon those parties.” Whether MoU 44 was that kind of agreement is open to dispute: by its first article it is a framework to negotiate toward provisional arrangements, not an agreement that settles the boundary, and the only compulsory conciliation yet conducted under the provision, the Timor-Leste case, left the question largely unanswered. Ending the MoU removed the agreement any such argument rested on, so the termination could only weaken Thailand’s case against conciliation, never Cambodia’s path to it.
Thailand has held in public that the island of Koh Kut is settled Thai territory, recognized since the 1907 treaty between France and Siam, with no negotiation open over it. The Article 298 exclusion for disputes that pull in an unsettled land-sovereignty question would require Thailand to point to such a dispute, and its own position that Koh Kut is settled leaves it none to point to.
Because the MoU is silent on termination, the rule that governs a withdrawal is the one codified in Article 56 of the Vienna Convention on the Law of Treaties. Thailand is not a party to that convention, and both states treat its terms as customary international law. Article 56 does not hand a state a clean exit on twelve months’ notice whenever a treaty says nothing about ending. It first requires showing that the parties meant to allow withdrawal or that a right to withdraw follows from the treaty’s nature, and only then the notice period. The formal notice such a withdrawal would take has not been given. Thailand’s own account is that it unofficially informed Cambodia. Cambodia’s government has said it received no formal notification under Articles 65 and 67 of the Vienna Convention.
Keo Rottanak gave the $300 billion figure to Reuters and, in a separate interview, to CNBC. Reuters reported the area, about 27,000 square kilometres, is “estimated to hold around 11 trillion cubic feet of natural gas, alongside large quantities of oil,” without stating who produced the estimate or how. No reserve assessment or field-development model behind either number has surfaced. The minister’s own framing stayed cautious about time. Development would take years, and “[i]f you are going to wait for decades more, the chances of attracting financing to do oil and gas exploration and exploitation may not be there.”
Cambodia drew its first crude from the Gulf of Thailand in late 2020, in a venture with the Singapore-listed firm KrisEnergy. Months later, KrisEnergy announced it was headed for liquidation. “Even if the two parties were to solve everything today, it will take time to ramp up financial resources and technology to do this,” Keo Rottanak said. TotalEnergies, which the minister named as an interested major, did not immediately respond to a request for comment from Reuters.
Cambodia has announced the conciliation route and has not yet filed it. In his 5 May statement, Prime Minister Hun Manet said Thailand’s withdrawal “would reject the only bilateral agreement, which constitutes the only bilateral framework that both parties have relied upon for more than two decades,” and that Cambodia would turn to UNCLOS compulsory conciliation. Keo Rottanak told Reuters the government “plans to reach out to the Thai side” on the mechanism. No record of a lodged conciliation request has appeared.
Thailand’s foreign ministry told Reuters it supports weighing options under the UN conventions, “but that it should be discussed bilaterally first.” The bilateral framework it points to is the one its cabinet ended on 5 May. Article 298 makes the compulsory conciliation Thailand would then face available once negotiations have failed to produce agreement. The agreement that held the dispute inside bilateral talks is the one Thailand chose to end.