The National Security Council of Thailand (NSC) has backed the unilateral cancellation of the bilateral maritime MoU with Cambodia. Thailand will instead negotiate with its counterpart through other mechanisms to settle long-standing Thai-Cambodian maritime disputes.

Following the NSC meeting on Thursday (23 April), Prime Minister Anutin Charnvirakul revealed that the NSC approved the cancellation of the 2001 Memorandum of Understanding on the maritime areas claimed by both Cambodia and Thailand, which has served as a framework for resolving maritime boundary disputes in the Gulf of Thailand between the two countries, according to several Thai news outlets.

The PM said that the proposal will be forwarded to the Cabinet as soon as possible.

The Thai side observed that despite being in force for decades, there has been no meaningful progress regarding the 2001 MoU. In addition, Cambodia recently ratified the United Nations Convention on the Law of the Sea (UNCLOS) in March. Thailand said this convention will be the primary framework for resolving the Thai-Cambodia maritime disputes.

PM Anutin also reiterated that Thailand can unilaterally cancel the MoU, but he did not provide further details.

According to government spokesperson Rachada Dhnadirek, no resolution has been reached from the five meetings held over the past 25 years under the 2001 MoU. Maritime disputes between the two countries were raised, but without any mutual agreement.

The cancellation would terminate negotiations under the MoU framework, noting that Thailand and Cambodia still have room to negotiate through alternative channels, without perpetuating the conflict. Cambodia can propose a mutually agreed framework.

According to the 2001 MoU, Thailand and Cambodia have an overlapping claims area of 26,000 square kilometres. Around 10,000 square kilometres north of latitude 11° North is still to be delimited, while the remaining area was designated as a Joint Development Area (JDA).

The overlapping area resulted from the two sides’ unilateral claims. Cambodia bases its claims on a domestic law of 1972, while Thailand relies on its 1973 continental shelf proclamation.

Significantly, Cambodia’s claimed line cuts through Thailand’s Koh Kut, which is not in line with international laws. Those who opposed the 2001 MoU believed that the line of Cambodia’s continental shelf claim places Thailand at a disadvantage, while experts asserted that the MoU does not constitute recognition of Cambodia’s claimed boundary. Further negotiations are still required to reach a mutually agreed settlement.

Previously, it has been debated whether Thailand can unilaterally cancel the MoU. Under the 2001 MoU, no specific agreement was made on cancellation. However, the 1969 Vienna Convention on the Law of Treaties states that in such cases, termination basically requires the consent of all parties, unless the nature of the treaty allows for unilateral withdrawal.

Phattharaphong Saengkrai of Thammasat University’s Faculty of Law, observed that the 2001 MoU is not a final settlement but rather ‘an agreement to negotiate’, which merely binds both parties to enter negotiations.

Basically, if negotiations fail to achieve the objectives, unilateral cancellation may be considered acceptable.

Amid rising nationalist sentiment linked to the conflict with Cambodia, several Thai nationalist groups have called on the government to unilaterally cancel the 2001 MoU on the grounds that the agreement could lead to the loss of territory, particularly Ko Kut.

Anutin’s Bhumjaithai seems to have seized the opportunity to capitalise on the sentiment.

The proposal to cancel the 2001 MoU was a part of the ruling Bhumjaithai Party’s election campaign, reflecting Anutin’s tough stance towards Cambodia, which resonated with patriotic voters and helped consolidate support for the Party in the latest election.

It later appeared in the policy statement delivered to parliament on 9 April, which stated that the government will expedite the study on the possible cancellation of the 2001 MoU.

Currently, land border disputes remain unresolved. In addition, a simmering tension between the two governments persists, fuelled by nationalist sentiments and a wave of hatred among people on both sides.

If Thailand proceeds with the cancellation, Thailand and Cambodia will have to restart efforts to resolve maritime disputes from the beginning. Renewed negotiations are likely to be challenging given the current situation.

This move could also undermine Thailand’s credibility on the international stage as a country that fails to adhere to a fundamental principle in both civil law and international law known as pacta sunt servanda (agreements must be kept). In addition, if Cambodia opposes Thailand’s unilateral cancellation, the issue could risk opening a new front in disputes with Cambodia.