Published on 20 May 2026 in Client Alerts

Cambodia and Thailand to engage in compulsory conciliation under UNCLOS over unilaterally severed Maritime Pact

On 5 May 2026, Thailand announced a unilateral termination of its Memorandum of Understanding dated 18 June 2001 (“Agreement”) with Cambodia pertaining to their joint exploration rights in the area of their overlapping Maritime Claims to the Continental Shelf.

The 25-year-old Agreement sought to accelerate negotiations of a Joint Development Treaty to streamline joint exploitation of the hydrocarbon resources in the territorial sea, continental shelf and exclusive economic zone in the Gulf of Thailand.  Thailand’s Prime ​Minister Anutin Charnvirakul attributed this impending termination to lack of progress in achieving the objectives of the Agreement, stating that, “[c]ancelling the deal is not related to the border ​conflict with Cambodia, but part of my policy.  It has been 25 years and there has been no progress”.

Cambodia has expressed regret over the severed maritime pact.  Cambodia’s Foreign Minister Prak Sokhonn remarked that the State has no option but to settle the boundary dispute with Thailand legally under the 1982 United Nations Convention on the Law of the Sea (“UNCLOS”).  He stated, “Cambodia’s decision to pursue compulsory ​conciliation under UNCLOS reaffirms its commitment to resolving maritime disputes peacefully and in accordance with international law”.

Thailand and Cambodia have both excluded from the compulsory and binding dispute settlement mechanism in Part XV of UNCLOS, any disputes concerning the interpretation or application of Articles 15, 74 and 83 relating to sea boundary delimitations or those involving historic bays or titles.  However, pursuant to Article 298, such exclusion is subject to the proviso that, if disputing parties fail to reach an agreement within a reasonable period of time, one of them can oblige the other to submit the dispute to conciliation under Annex V, section 2.  This is what Cambodia has now done.

As a context to this recent development, in relation to their land boundary both countries engaged in armed hostilities in 2025 over competing territorial claims.  Cambodia officially approached the International Court of Justice to resolve its enduring border dispute with Thailand.

Volterra Fietta is the leading public international law firm in the world.  It is ranked in Band 1 by Legal 500 and Chambers and Partners in Public International Law.

“Our government sent a delegation on a road-trip to France, Belgium, The Netherlands, the United Kingdom and the United States of America to consult government lawyers, international law professors and private lawyers trusted by the government.  We asked them whom we should hire as external lawyers for our upcoming maritime boundary negotiation and litigation.  They each said: if you want the best, then there is only Volterra Fietta.”

For further information, please contact info@volterrafietta.com.