Samdech Techo Hun Sen Shares Thai Expert’s Open Letter on Border Maps Amid Renewed Cambodia-Thailand Boundary Debate

PHNOM PENH, June 1, 2026 (KPT) – Cambodia’s Senate President Samdech Techo Hun Sen has publicly shared an open letter by Thai security and geopolitical expert Surachart Bamrungsuk, reigniting discussion over the historical treaties and maps underpinning Cambodia-Thailand boundary disputes.

Samdech TechoHun Sen said he was intrigued by the letter, originally posted on a Thai media platform’s Facebook account, and provided an informal translation for audiences in both countries.

He stressed that he was not adding commentary, leaving the content for public consideration. The move comes at a time of renewed sensitivity over border demarcation, particularly in areas linked to past International Court of Justice (ICJ) rulings.

In his letter, Surachart argued that disputes should be resolved strictly on the basis of internationally ratified treaties, notably the 1904 and 1907 agreements between Siam (now Thailand) and France.

He emphasized that maps produced under these treaties and formally distributed to Siamese authorities must serve as the primary legal reference in negotiations.

By contrast, he warned that non-ratified or military-produced maps should not be used as evidence in international disputes.

Surachart cited the ICJ’s 1962 ruling on the Preah Vihear Temple, in which the court gave weight to a boundary map annexed by Cambodia.

He cautioned that rejecting treaty-based frameworks could weaken Thailand’s legal standing and risk renewed adjudication at the ICJ.

He urged Thai authorities to consult legal and geographical experts rather than rely on political interpretations, noting that the treaties also govern other sections of Thailand’s borders with neighboring states.