Cambodia says Thai trench breaches ceasefire commitments, ‘cannot redraw border’

A Thai flag flies over Cambodian territory. The foreign ministry has repeatedly protested the construction of permanent infrastructure on occupied land. Defence ministry

Cambodia has accused Thai armed forces of breaching ceasefire-related commitments by using heavy machinery to construct an earthen trench near Boundary Pillar No. 9 in Oddar Meanchey province, reiterating that unilateral changes on the ground cannot redraw the international border.

The Ministry of Foreign Affairs and International Cooperation lodged a formal protest against Thailand over the alleged activity, which it said took place on September 15 in the Ta Tum area of Anlong Veng district.

In a September 16 press release, the ministry described the construction as another violation of Cambodia’s sovereignty and territorial integrity along the Cambodia-Thailand border.

“The Royal Government of Cambodia has formally lodged another strong protest against Thailand’s further violations of Cambodia’s sovereignty and territorial integrity along the border,” it said.

According to the ministry, Thai forces used heavy machinery to level the ground and build the trench in the vicinity of Boundary Pillar No. 9.

Cambodia argued that the activity violated its sovereignty and territorial integrity as defined and delimited by the 1:200,000-scale maps produced by the commissions responsible for determining the boundary between French Indochina and Siam under the Franco-Siamese Convention of 1904 and the Treaty of 1907.

The government also said the construction breached Article 5 of the 2000 Memorandum of Understanding between Cambodia and Thailand on the Survey and Demarcation of the Land Boundary.

The article requires both sides to refrain from carrying out work that changes the environment of the frontier zone while the joint survey and demarcation process remains underway.

Cambodia said the alleged construction also violated the Joint Statement adopted at the third special meeting of the General Border Committee on December 27, 2025.

Under that statement, Cambodia and Thailand agreed to refer border survey and demarcation issues to the Joint Boundary Commission (JBC) and enable it to resume its work as soon as possible in accordance with their existing agreements.

The ministry’s protest places the trench within the wider dispute over whether military positions or structures established on the ground can affect sovereignty after the ceasefire.

Cambodia maintains that fortifications, fences, razor wire, shipping containers or troop deployments cannot establish a new boundary, particularly in areas where technical survey and demarcation work has yet to be completed by the JBC.

“The Royal Government of Cambodia re-emphasises that it does not accept any boundary line or territorial claim unilaterally asserted by Thailand,” the ministry said.

It added that the Thai activity would not prejudice Cambodia’s legal rights or position regarding its international boundary.

The statement reinforces Cambodia’s position that the ceasefire was intended to end hostilities and create conditions for peaceful negotiations, rather than legitimise troop positions or physical structures erected along the frontier.

Cambodian officials have repeatedly argued that the locations occupied by military forces when the ceasefire took effect cannot be interpreted as an agreed border or used to determine sovereignty.

Any unresolved question must instead be addressed by the JBC through technical survey and demarcation based on the existing treaties, maps and bilateral agreements accepted by the two countries, according to the Cambodian position.

The government demanded that Thailand cease the alleged construction and honour its commitment to de-escalating tensions, fostering mutual trust and facilitating a peaceful resolution of border disputes.

It said compliance with those commitments was necessary to restore peace, stability and good-neighbourly relations along the Cambodia-Thailand frontier.

“Cambodia remains committed to resolving all boundary disputes with Thailand, as with all its neighbours, exclusively through peaceful means, in line with international law and existing bilateral agreements,” the ministry stated.

It stressed its firm position that borders must not be changed through force.

The latest protest comes amid continuing disagreement over military activities and the construction of physical infrastructure at several locations along the shared border following the 2025 armed clashes.

Cambodia has accused Thai forces of attempting to create new facts on the ground in areas awaiting formal survey and demarcation.

It has maintained that no such activity can override the established bilateral border mechanisms or alter either country’s legal position.

The ministry’s statement did not indicate whether the trench construction had stopped or whether the area would be inspected jointly by Cambodian and Thai officials.

-Phnom Penh Post-