Thailand’s energy security outlook opens as the cancellation of MOU 44 may lead to the application of UNCLOS 1982, which ultimately might benefit no side at all rather than either party.
In any case, once the Cabinet decides to cancel the 2001 Memorandum of Understanding (MOU 44) between Thailand and Cambodia regarding overlapping maritime claims, MOU 44 the Ministry of Foreign Affairs, as the implementer, must follow the procedures stated in the final paragraph of Article 56 of the 1969 Vienna Convention on the Law of Treaties (VCLT). Although Thailand is not a party to the Convention, this is considered customary international practice requiring notification to the other party within 12 months.
What happens next is entirely speculative and depends on how the Cambodian government responds and how the situation develops. The benefits or harms depend on how high the Thai side sets its goals, how willing it is to compromise, and how much it is prepared to accept the consequences. Various scenarios can be outlined as follows.
Scenario 1 This is the scenario Thailand most desires, where Cambodia agrees with Thailand's proposal and accepts that its continental shelf claims are excessive under international law, thus agreeing to reduce its claimed area to about 5,000–7,000 square kilometers of overlap. This area would be jointly developed for petroleum resources, with benefits and costs shared as agreed.
Achieving this objective satisfactorily for both sides would likely take considerable time. Drawing from the experience between Thailand and Malaysia, the process took 33 years—from initial friendly maritime boundary talks in 1972 until an agreement on joint development and natural gas utilization was reached in 2005.
Scenario 2: Cambodia disagrees with the cancellation of MOU 44, creating a new dispute, but remains willing to negotiate bilaterally to establish a new agreement. It is also possible both sides might use this issue as leverage to gain concessions. For instance, Cambodia might insist on negotiating only joint development and benefit sharing, postponing maritime boundary delimitation until the joint development area’s resources are exhausted or for a fixed period, such as 50 years—similar to the Thailand-Malaysia case. Thailand would maintain its original goal of reducing the overlap to resolve the Ko Kut island issue, or else insist on cancellation.
This scenario reflects the period from 1970 to 2001 when both sides held rigid positions without compromise. It essentially rewinds the clock over half a century to start anew. If bilateral relations remain unstable, it may take many generations before natural gas resources can be exploited. By then, production costs may be prohibitively high.
Scenario 3 Cambodia refuses to cancel and no longer wishes to negotiate bilaterally with Thailand but agrees to resolve the dispute under the framework of the United Nations Convention on the Law of the Sea 1982 (UNCLOS 1982), in line with Thailand’s preference, leading to several sub-scenarios: Scenario 3.1
Cambodia expresses disagreement with the cancellation of MOU 44 but initially refrains from invoking any formal dispute resolution mechanisms. Instead, it seeks to build public perception and a narrative to enhance its credibility and undermine the opposing side. This reflects Cambodia’s awareness that Thailand has reserved its jurisdiction regarding the Law of the Sea Tribunal and the International Court of Justice, fearing a repeat of the Preah Vihear temple dispute. Such tensions can increase international strain and make compromise difficult, potentially leading to undesirable incidents. Scenario 3.2
Both Thailand and Cambodia are parties that have ratified UNCLOS. Either party may initiate dispute resolution under Part 15, which offers options such as conciliation, where one party starts the process by notifying the other in writing about the dispute. The parties may nominate conciliators to form a commission, which determines the procedure by inviting oral or written submissions. Decisions are made by majority and presented as non-binding recommendations. Parties may choose whether to comply; if both agree, the issue may be resolved, otherwise it remains unresolved.
Scenario 3.3
If friendly conciliation fails, UNCLOS provides for compulsory conciliation, which proceeds regardless of a party’s acceptance or non-response. Though it compels continuation of the process, it cannot enforce compliance. For legally binding decisions under Part 15, parties may use one of the following:
(1) The International Tribunal for the Law of the Sea (ITLOS) as per Annex VI,
(2) The International Court of Justice (ICJ),
(3) Arbitration under Annex VII,
(4) Arbitration under Annex VIII.
However, legal debates exist regarding the choice of mechanism. For example, a party cannot unilaterally initiate these processes if the other has made a reservation under Article 298, particularly concerning boundary disputes and military activities.
Nonetheless, under Annex VII arbitration, a party can unilaterally proceed. Article 9 of Annex VII clearly states,
“Failure to appear or defend the case does not impede proceedings.” Provided the tribunal has jurisdiction and the claim is legally valid, the arbitral decision is final and legally binding. Despite these UNCLOS-based scenarios and mechanisms, uncertainty remains regarding timing and practical outcomes. For example, in the China-Philippines case, arbitration took three years from initiation to ruling, while Timor-Leste and Australia took two years using compulsory conciliation to reach a new agreement.
Key considerations when using UNCLOS mechanisms include: first, although UNCLOS proceedings may conclude in two to three years, experience from the Philippines-China case shows such rulings do not necessarily end disputes,
because despite being legally binding, there is no enforcement mechanism to compel compliance. If a party rejects or ignores the ruling, international mechanisms cannot enforce it, and disputes persist. However, if both parties agree to compromise, as in the Timor-Australia case, they can effectively resolve boundary issues and share petroleum resource benefits, albeit with some delays.
Second, current global geopolitical dynamics exert significant energy pressures on Thailand. Combined with declining natural gas production from various Gulf of Thailand fields—including Thai continental shelf sources, Thailand-Malaysia joint developments, and imports from Myanmar's Mottama Gulf—Thailand must seek more stable energy supplies elsewhere. Achieving an agreement with Cambodia promptly, by any approach, would greatly benefit Thailand’s energy security.
Prolonged delays mean existing Gulf of Thailand offshore infrastructure will deteriorate over time. Restarting operations would require increased investment, delay resource extraction, raise costs, and increase economic opportunity losses.
Ultimately, the outcome depends on how much both parties are willing to compromise and their understanding of the essence of international cooperation for mutual benefit. If each side focuses solely on its own interests and pursues a win-lose approach without concessions, the dispute may end sadly with no one gaining anything.