Thailand’s cabinet formally cancelled Memorandum of Understanding 44 on May 5, 2026, terminating its last remaining cooperative framework for joint offshore energy exploration with Cambodia and pushing a dispute over an estimated USD 300 billion hydrocarbon zone in the Gulf of Thailand into international legal proceedings.
Key Facts At A Glance
- Thailand’s cabinet voted to cancel MOU 44 on May 5, 2026, on the announcement of Prime Minister Anutin Charnvirakul
- MOU 44 was signed in June 2001 by then-Prime Ministers Thaksin Shinawatra and Hun Sen to create a joint exploration framework for the Gulf of Thailand’s Overlapping Claims Area
- The Overlapping Claims Area spans approximately 26,000 to 27,000 square kilometers and is estimated to hold up to 11 trillion cubic feet of natural gas and up to 300 million barrels of oil and condensate
- Cambodia’s Foreign Minister Prak Sokhonn announced on May 5, 2026, that Phnom Penh will initiate compulsory conciliation proceedings under the United Nations Convention on the Law of the Sea
- Thailand’s Foreign Ministry stated UNCLOS will serve as the reference framework for future bilateral negotiations on maritime boundary demarcation
- A ceasefire between Thailand and Cambodia has been in place since late December 2025 following two rounds of armed conflict along their shared 817-kilometer border that killed close to 150 people and displaced hundreds of thousands
- MOU 44’s cancellation was a campaign pledge of Prime Minister Anutin, who became the first Thai premier reelected in two decades on a nationalist platform
From Cooperation Framework To Legal Dispute
The Gulf of Thailand’s Overlapping Claims Area has been one of Southeast Asia’s most consequential unresolved energy disputes for more than five decades. Cambodia delineated its maritime claim in 1972 and Thailand filed a counterclaim in 1973, creating an overlapping continental shelf zone that analysts have estimated holds hydrocarbon resources valued at a minimum of USD 300 billion. MOU 44, signed in June 2001 under the governments of Thaksin Shinawatra and Hun Sen, was designed as a dual-track instrument: it proposed creating a framework for joint hydrocarbon exploration in the overlapping zone while simultaneous negotiations continued on formal maritime boundary demarcation.
Despite its structure, the agreement produced no operational progress over 25 years. Political instability in Thailand, recurring border tensions, fierce nationalist opposition, and legal ambiguities over the agreement’s demarcation language repeatedly derailed substantive negotiations. The Thai Office of the Council of State raised concerns that certain wording in the MOU could be legally challenged in domestic courts, and Thai bureaucrats faced personal legal exposure under Article 157 of the 2017 Constitution for signing off on policy that could be construed as compromising territorial sovereignty.
The Anutin Cabinet’s Decision
Prime Minister Anutin Charnvirakul, who won re-election earlier in 2026 on a platform of Thai nationalism hardened by two rounds of armed conflict with Cambodia in 2025, had made the cancellation of MOU 44 a formal campaign pledge. Following the cabinet vote on May 5, Anutin told reporters the decision was a matter of policy and not a response to the border conflict, stating the pact had produced no results in 25 years. Thailand’s Foreign Ministry confirmed that UNCLOS would now serve as the reference for direct bilateral negotiations on maritime boundary demarcation. Separately, Thailand is also considering whether to cancel MOU 43, the companion land boundary instrument signed in 2000, which remains in effect.
Cambodia’s UNCLOS Response
Cambodia’s Foreign Minister Prak Sokhonn responded on the same day, May 5, stating Phnom Penh would pursue compulsory conciliation under UNCLOS as it had “no option” to resolve the maritime dispute within an internationally recognized legal framework. Sokhonn affirmed that the cancellation of MOU 44 does not affect Cambodia’s maritime rights under international law. The invocation of UNCLOS compulsory conciliation introduces a formal multilateral legal process that can be both lengthy and politically complex, and which Thailand has historically resisted, having previously declined Cambodian requests to submit disputes to the International Court of Justice.
Energy Security And Commercial Implications
Thailand’s domestic energy position gives the dispute real commercial urgency. Thailand currently has 34 active petroleum exploration and production projects in 47 fields in the Gulf of Thailand, but domestic gas production meets only approximately 28 percent of the country’s power generation needs. Thailand imports the balance as liquefied natural gas, primarily from Malaysia and Qatar, and as pipeline gas from Myanmar. Analysts have estimated that resolving the OCA and proceeding to joint development could extend Thailand’s offshore gas supply by at least 20 years. Without MOU 44 in place, no legal framework exists for commercial exploration or development in the disputed zone. Energy companies that had been monitoring the OCA for potential concession opportunities now face an indefinite hold, pending the outcome of UNCLOS proceedings that could take years to resolve.