Thailand has formally appointed two former presidents of the International Tribunal for the Law of the Sea as its conciliators for its maritime dispute proceedings with Cambodia. The move marks the latest step in a compulsory conciliation process that emerged after Thailand moved to terminate the maritime MoU that had long served as the framework for bilateral negotiations. 

Prachatai brings together the key facts on how Thailand's push to scrap the maritime MoU with Cambodia led the two countries to compulsory conciliation under the United Nations Convention on the Law of the Sea (UNCLOS).

Thailand and Cambodia entered into the Memorandum of Understanding regarding the Area of Overlapping Claims between Thailand and Cambodia in 2001. The MoU provided the framework for negotiating their maritime disputes, which covers around 26,000 sq km. 

In 2023, amid concerns over energy security, the government under former Prime Minister Srettha Thavisin announced plans to accelerate negotiations with Cambodia. This policy direction continued under the administration of former PM Paetongtarn Shinawatra.

This initiative was abandoned after she was ousted by the Constitutional Court over a leaked call with former Cambodian PM Hun Sen. At the same time, conservative political forces intensified calls for Thailand to scrap the 2001 MoU due to concerns over Cambodia's maritime line, which intersects Thailand’s Koh Kut.

During the 2026 election campaign, Anutin Charnvirakul’s Bhumjaithai Party chose to align itself with the nationalist sentiment by pledging that if elected, the party would cancel the 2001MoU. 

The Bhumjaithai Party eventually won the election. Critics argued that one key factor leading to the Party’s victory was its tough stance toward Cambodia, together with the general public’s lingering resentment over last year’s armed clashes. 

Coincidentally, Cambodia formally ratified UNCLOS in March, while Thailand ratified in 2011. Thailand and Cambodia are now bound by the same legal framework under UNCLOS.

UNCLOS is an international treaty that sets the rules governing the world's oceans. These rules cover matters ranging from the delimitation of maritime zones to mechanisms for resolving disputes between states, such as the overlapping claims area between Thailand and Cambodia.

Before a state can be bound by provisions in an international treaty, it must formally consent to this through a process known as ratification. Once both disputing states have ratified UNCLOS, the mechanisms provided under the Convention, including its dispute resolutions, can be invoked at any time.

In April, Thailand announced that mechanisms under UNCLOS would be used to resolve the maritime disputes with Cambodia. At the time, however, Thailand did not unequivocally state which mechanism it wished to use. 

Considering Thailand's previous stance, the government repeatedly stated that it prioritised bilateral negotiations with Cambodia. While bilateral negotiations are also considered one of the mechanisms under UNCLOS, some critics argued that the broadly worded announcement gave Cambodia room to invoke other UNCLOS mechanisms.

Cambodia, as the newest member of UNCLOS, then responded swiftly by announcing that it would also adopt UNCLOS mechanisms as its primary approach for resolving the maritime dispute. At that point, the two countries appeared to be on the same page.

On 5 May, the Thai Cabinet approved the cancellation of the 2001 MoU on the grounds that negotiations had made no progress. The PM also asserted that the negotiations will be conducted through international mechanisms under UNCLOS.

At the same time, Cambodian PM Hun Manet quickly announced to the public through his Facebook page that Cambodia planned to pursue Compulsory Conciliation. It was the first time that the mechanism had been mentioned.

“Cambodia would be left with no choice but to rely upon international law and the United Nations Convention on the Law of the Sea (UNCLOS), particularly the mechanism of Compulsory Conciliation under this Convention,” stated the Cambodian PM.

Compulsory Conciliation is one of the dispute resolution mechanisms under UNCLOS, and involves a Conciliation Commission acting as a third party. A party wishing to invoke the mechanism can unilaterally initiate it by notifying the Secretary General of the United Nations and the other party. Failure of the other party to respond is no bar to the proceedings.

According to Article 298, a state is allowed to opt out of a certain dispute resolution mechanisms under UNCLOS, but must remain subject to Section 2 in Annex V, which deals with compulsory conciliation. 

Thailand has declared that it does not accept the courts’ jurisdiction regarding maritime boundary delimitation disputes. Even though Cambodia cannot take the case to the international courts, Compulsory Conciliation allows Cambodia to initiate proceedings unilaterally, presenting Thailand with a situation it could not avoid.

The mechanism employs five Conciliators. Each party is required to appoint two Conciliators. These four then select a fifth to chair the Conciliation Commission. 

The Commission will hear the parties, examine their claims and objections, and make proposals to the parties with a view to reaching an amicable settlement.

Once the Commission is formed, the Conciliators have to issue a report within 12 months, recording any agreements reached or failures to agree. 

The Commission’s report will also include recommendations. The involved parties have to enter into a bilateral agreement to resolve the disputes based on the recommendations in the report. Unlike the verdicts of a court or arbitration, the Commission’s recommendations do not legally bind the parties.

If Thailand and Cambodia remain unable to reach a mutual agreement, the next step would involve bringing the case to the international courts, provided that both parties give ‘mutual consent’. 

Cambodia’s announcement caused unease in Thailand and appeared to upend Thailand’s expectations. By invoking the mechanism, Cambodia brought a third party into the dispute resolution process, despite Thailand's preference for bilateral negotiations.

On 2 June, Cambodia presented Thailand with a fait accompli by formally submitting a petition with the Secretary General of the United Nations to invoke Compulsory Conciliation. 

Cambodia has appointed its two conciliators: Danish ambassador Peter Taksøe-Jensen, and Jean-Marc Thouvenin, Secretary General of The Hague Academy of International Law.

Thailand attempted to push back against Cambodia’s move. Thai Foreign Minister Sihasak Phuangketkeow responded by arguing that Cambodia had skipped a step and that bilateral negotiations should take place first. However, the Thai government reassured its domestic audience that it had prepared for all possible scenarios and would not be placed at a disadvantage.

Significantly, Thailand also affirmed its stance that compulsory conciliation proceedings would be limited to maritime delimitation and would not cover negotiations on the joint development area.

Given Cambodia’s latest move, Thailand had no choice but to appoint its two conciliators. On Tuesday (16 June), Thailand formally appointed German Rüdiger Wolfrum and South African Albert Hoffmann. Both are former Presidents of the International Tribunal for the Law of the Sea. 

The four appointed conciliators have to meet within 30 days to select a fifth to chair the Conciliation Commission. Once the Conciliation Commission is formed, the conciliation process will formally begin.