PHNOM PENH, July 20, 2026 — Cambodia has reaffirmed its commitment to resolving both maritime and land border disputes with Thailand through peaceful means and in accordance with international law, while Japan has launched a new chapter in bilateral security cooperation by providing its first Official Security Assistance (OSA) package to Cambodia.

The twin developments come as Southeast Asia faces growing geopolitical uncertainty, marked by unresolved territorial disputes, intensifying strategic competition among major powers, and increasing reliance on international legal mechanisms to manage regional tensions.

In a statement issued on Sunday, Government Spokesperson Pen Bona said Cambodia remains committed to pursuing the peaceful settlement of overlapping maritime claims with Thailand through the Compulsory Conciliation mechanism under the United Nations Convention on the Law of the Sea (UNCLOS).

According to the statement, the four independent conciliators—two appointed by Cambodia and two by Thailand—have agreed to extend the timeframe for selecting the Chair of the Conciliation Commission. The government said the extension would not affect any procedural deadlines established under UNCLOS but would allow sufficient time to ensure the appointment of an independent and impartial chairperson.

"Cambodia remains firmly committed to advancing the peaceful settlement of the maritime dispute with Thailand under international law and the UNCLOS conciliation process," Pen Bona said.

The spokesperson said Cambodia continues to regard the UNCLOS conciliation mechanism as the most appropriate legal avenue after Thailand unilaterally withdrew from the 2001 Memorandum of Understanding (MoU 2001), which had served for more than two decades as the bilateral framework for negotiations over overlapping maritime claims in the Gulf of Thailand.

Prime Minister Hun Manet announced on 2 June 2026 that Cambodia would formally invoke the compulsory conciliation provisions under UNCLOS following Thailand's decision to terminate the MoU. Cambodian officials have argued that, after reviewing all available peaceful dispute-settlement options, the UNCLOS process provides both countries with an opportunity to present their legal positions before an independent panel of international experts.

Although the Conciliation Commission's recommendations are not legally binding in the same way as a judgment of an international court, Phnom Penh believes the process carries significant diplomatic and legal authority and could lay the foundation for a mutually acceptable and sustainable settlement.

Cambodia has also reaffirmed its position on the two countries' land border, emphasizing that it remains committed to resolving outstanding issues peacefully while respecting international law and existing bilateral agreements.

Pen Bona said Cambodia continues to observe the ceasefire arrangements, the Joint Communiqué of 27 December 2025, the Kuala Lumpur Joint Statement of 26 October 2025, and other bilateral understandings reached between Phnom Penh and Bangkok.

He added that Cambodia continues to uphold the international legal principle of Uti Possidetis Juris, relying on the Franco-Siamese treaties, officially recognized boundary maps, border demarcation records and other legal instruments as the basis for determining the international boundary.

"Cambodia does not recognize any attempt to alter internationally recognized borders through the use or threat of force and will continue to safeguard its sovereignty through peaceful and lawful means," Pen Bona said.

While Cambodia has emphasized diplomacy and international law in addressing its border disputes, Japan has simultaneously expanded security cooperation with Phnom Penh through its Official Security Assistance (OSA) framework.

On 19 July, Japanese Ambassador UENO Atsushi and Cambodia's Deputy Prime Minister and Minister of National Defence General Tea Seiha signed and exchanged diplomatic notes for an OSA grant worth 500 million yen (approximately US$3 million), marking the first time Cambodia has received security assistance under the program.

According to the Embassy of Japan, the assistance package will provide communication equipment for the Royal Cambodian Army and patrol boats for the Royal Cambodian Navy.

"The project aims to strengthen Cambodia's defense capabilities and contribute to peace, stability and security in the region," the Embassy of Japan said in its official statement announcing the agreement.

 

Japan introduced the Official Security Assistance framework in 2023 as part of its broader security policy to support like-minded partners in strengthening defensive capabilities and promoting a stable and rules-based Indo-Pacific. Cambodia's inclusion in the program represents a significant milestone in bilateral defense relations between the two countries.

Taken together, Cambodia's continued reliance on international legal mechanisms to address border disputes and Japan's decision to deepen security cooperation illustrate two parallel trends shaping Phnom Penh's foreign and security policy. On one hand, Cambodia is seeking to resolve longstanding territorial issues through diplomacy and international law. On the other, it is expanding practical defense cooperation with international partners to strengthen national resilience in an increasingly uncertain regional security environment.

For regional observers, the developments underscore Cambodia's effort to balance the protection of its sovereignty with broader diplomatic engagement, while reinforcing partnerships that support peace, stability and security across the Indo-Pacific.