Thailand’s cabinet has approved withdrawal from the 2001 maritime memorandum with Cambodia and kept the 2000 land boundary memorandum in place. The Senate’s ad hoc committee on the two agreements has urged scrapping both. The committee’s report on the 2000 land agreement is now before the full Senate.
On 24 March the committee chairman, Senator Noppadon Inna, announced that the panel had unanimously voted to recommend revoking the 2000 agreement, popularly known as MOU 43, after more than twenty meetings, field visits to seven Thai-Cambodian border provinces, and briefings from security agencies and the Ministry of Foreign Affairs. The committee enumerated six reasons. The first names the 1:200,000-scale maps embedded in the agreement as defective and in conflict with Thailand’s 1:50,000 series, and identifies the Joint Boundary Commission as lacking authority over encroachment. The second concerns the constitutional procedure under which a previous cabinet adopted MOU 43. The third cites Cambodia’s 1993 Constitution and its mandated 1:100,000-scale map. The fifth points to the border situation as fundamentally changed after the 2025 clashes, with Thailand relying instead on the General Border Committee joint statement of 27 December 2025. The sixth alleges a pattern of Cambodian non-compliance the agreement is said to be insufficient to address. The committee invoked Article 60 of the Vienna Convention on the Law of Treaties as authority for unilateral withdrawal, with three months’ notice. It said post-revocation Thailand and Cambodia would still rely on the 1904 Convention, the 1907 Treaty, and the 1995 border cooperation agreement.
Prime Minister Anutin Charnvirakul said in February that MOU 43 benefits Thailand and that disagreements should be resolved diplomatically. On 31 March Anutin confirmed only MOU 44 would be included in the government policy statement to Parliament, the cabinet’s programme for the legislative session. In late April Foreign Minister Sihasak Phuangketkeow said MOU 43 was not for immediate cancellation. On 5 May the cabinet approved Thailand’s withdrawal from MOU 44. MOU 43 remains in force. No Article 65 written notification has been issued on either agreement. The Senate committee’s recommendation on MOU 43 awaits full Senate consideration; the cabinet has not adopted it.
The committee’s six reasons route through the 1904 framework and the 1995 cooperation agreement, the documentary architecture the committee proposes will continue to operate after MOU 43 is revoked. The first reason, that the 1:200,000-scale maps embedded in MOU 43 are defective, names the same map series the International Court of Justice analyzed in 1962. The Annex I map, one sheet of an eleven-sheet series produced by the Franco-Siamese Commissions of Delimitation, was at the center of the Court’s 1962 finding that Thailand had accepted the map by conduct.
The Court held that the acceptance of the Annex I map by the parties caused it to enter the treaty settlement and become an integral part of it. Thailand, the Court found, by its 1908-1909 conduct and subsequent acts, was bound by the Annex I map line. The Judgment ruled on sovereignty over the region of the Temple of Preah Vihear. The 2013 Interpretation Judgment declined to extend the binding-force finding to the full boundary line. The 2013 Court held the territorial scope of the 1962 dispositif covered the promontory of Preah Vihear, extending in the north to the Annex I map line but not beyond. What survives, on the Court’s own framing, is Thailand’s acceptance of the Annex I map as a product of the delimitation work the 1904 Convention required.
MOU 43 was not a fresh cartographic instrument. Article I provides that survey and demarcation of land boundary “shall be jointly conducted in accordance with” the 1904 Convention, the 1907 Treaty and its protocol on delimitation, and “Maps which are the results of demarcation works” of the Franco-Siamese Commissions of Delimitation under those treaties. The 1:200,000 series the committee identifies as defective is the cartographic record those treaties produced. Revocation of MOU 43 dismantles the bilateral commission and the survey mechanism. It does not dissolve the senior instruments or the maps incorporated through them.
The committee’s fifth reason, the changed border situation after the 2025 clashes, tracks the language Article 62 of the Vienna Convention codifies as fundamental change of circumstances. Article 62(2)(a) provides that fundamental change cannot be invoked to terminate a treaty “if the treaty establishes a boundary.” Cambodia’s State Secretariat of Border Affairs cited this provision in its 26 March response, framing MOU 2000 as a border-related treaty within 62(2)’s reach. Whether MOU 43 itself, as a survey and demarcation instrument operating under the 1904 and 1907 treaties, falls within 62(2)(a)’s “establishes a boundary” scope is a question the committee did not publicly engage. Article 62(2)(b) provides that fundamental change cannot be invoked when the change results from the invoking party’s own breach. Neither bar is procedural; both are textual.
Senator Noppadon’s invocation of Article 60 for material breach carries a procedural architecture the committee did not address publicly. Article 65(1) of the Vienna Convention requires written notification specifying the measure proposed and the reasons. Article 65(2) provides a three-month minimum objection period after notification, not three months as substitute for notification. Article 67(2) requires the instrument of termination be conveyed by the Head of State, Head of Government, or Foreign Minister, or by a representative producing full powers, the VCLT term for the authorization to represent a state in treaty acts. For a treaty without a termination clause, Article 56(1) holds that the treaty is not subject to denunciation unless it is established that the parties intended to admit the possibility or a right of denunciation may be implied by the nature of the treaty. MOU 43 contains no termination clause. Where the substantive bar in 56(1) is overcome, Article 56(2) sets the notice floor at not less than twelve months.
The Article 60 allegations sit on the committee’s public record as asserted grounds for material breach: construction of structures along the border, the laying of landmines, and military weapons used against Thai civilians. Cambodia’s SSBA response cited Article 62(2) and the principle of uti possidetis juris, the doctrine that newly independent states inherit the boundaries established in the colonial period. The SSBA did not engage publicly with the committee’s specific Article 60 allegations. It also did not deploy Article 65’s procedural requirements as public counter-position. The gap is on the documentary record.
The committee’s third reason cites Cambodia’s 1993 Constitution. Article 2 provides that “the territorial integrity of the Kingdom of Cambodia shall never be violated within its borders as defined in the 1/100,000 scale map made between the years 1933-1953, and internationally recognized between the years 1963-1969.” The committee’s argument is that maps produced under MOU 43 may not be recognized by Cambodia, rendering negotiations futile. Article 2 anchors Cambodia’s territorial integrity to a specific cartographic record. It constrains what Cambodia can accept in demarcation outcomes. It does not preclude the survey and demarcation work the MOU framework was set up to conduct.
The Thai Foreign Ministry’s public communications describe MOU 2000 as the operative bilateral framework using the Joint Boundary Commission mechanism. Thailand’s 19 January 2026 UN filing committed to addressing all legal and technical matters within the MOU 2000 framework. The Senate committee, in March, recommended its cancellation. The cabinet, through February, March, and late April, treated it as one to preserve. This publication documented the same pattern of Thai institutional contradiction on the same instrument in March 2026. The SSBA’s 26 March statement listed JBC achievements that include identification of all seventy-four French-era boundary pillars, the joint geodetic network, placement of temporary markers, and detailed surveys at border checkpoints. Article 70 of the Vienna Convention provides that termination “does not affect any right, obligation or legal situation of the parties created through the execution of the treaty prior to its termination.” The execution survives revocation.
The committee’s strongest reason is that the bilateral mechanism has not produced demarcation. After twenty-six years, the committee said, only sixty percent of the first phase is complete. That is a political argument about performance. It is not a legal route for unilateral revocation. MOU 43 contains no termination clause. The substantive bar under Article 56(1) and the procedural requirements under Articles 65 and 67 have not been met. The boundary treaty exception in Article 62(2)(a) operates on the convention’s own text. The architecture the committee would leave in place includes the 1904 Convention, the 1907 Treaty, the maps the Commissions of Delimitation produced under them, and the ICJ 1962 finding on Thailand’s acceptance of the Annex I map by conduct. That architecture is what any subsequent Thai claim would be measured against.