Chouk Chey and Nong Chan face each other across the same ground. So do Prey Chan and Nong Ya Kaeo. In October 2025 Cambodian and Thai officials meeting in Chanthaburi put both pairs into one joint statement. They named the stretch of border those villages sit on as the run between Boundary Pillars 42 and 47, and they agreed what would happen there and in what order.
Boundary pillars are concrete markers set along the frontier long ago. Their numbers are how the two sides refer to stretches of border they cannot yet describe any other way. Along this one the pillars follow a straight line drawn under a 1907 treaty, Thailand’s foreign ministry says. Fixing the line on the ground between two pillars is a different job from saying where the border runs, and the two have never meant the same thing.
The sequence starts with a technical instruction, which is the written method the survey teams would work to. The joint survey comes next, with temporary markers put in the ground. Those markers serve the survey only, the document says, and do not affect the international boundary. Then both sides approve the result, and then each consults inside itself. Last comes what the document calls the adjustment of land occupation. Who lives where, in other words. The two sides wrote that they would decide the mechanism for that later, and they have not said what it will be.
On 8 September 2026 the Cambodian foreign ministry lodged a protest over four sets of work it says Thai armed forces carried out between 31 August and 7 September. Two of the four places are Chouk Chey and Prey Chan.
The ministry says Thai forces demolished two civilian houses at Boeung Trakoun in Banteay Meanchey province on 31 August, then levelled the ground and raised an earthen bank on it. In the first days of September, it says, they brought machinery to build fortifications near a pagoda in O Smach commune, in Oddar Meanchey province. Then a well drilled at Chouk Chey. On 7 September, civilian structures demolished at Prey Chan.
The release adds one more item. It says that on 7 September a Thai air chief marshal took an observer team from ASEAN, with Thai and foreign media, to view buildings at O Smach. The visit, the ministry says, amounted to an unlawful assertion of Thai administrative authority. Both governments describe that visit. What they disagree about is what it meant.
The rest of the list is the ministry’s account alone. Nothing outside the Cambodian government describing any of the four sets of work has surfaced, and reporters reach three of these places rarely.
Cambodia names two texts as violated. One is the memorandum the two sides signed on 14 June 2000 on surveying the land border and fixing the line. The other is the joint statement of 27 December 2025, agreed after a General Border Committee meeting, which set the current ceasefire. The release cites no article, item or paragraph of either.
The provision the two ministries reach for in complaints of this kind is Article V of the 2000 memorandum. It binds the authorities of either Government and their agents. What sets it off is any work resulting in changes of environment of the frontier zone, meaning the belt of land along the border. That reaches wider than military work, and it does not turn on which side of the line the work sits. The clause lets one thing through: work by the Joint Technical Sub-Commission in the interest of the survey and demarcation. That sub-commission is the technical body the joint boundary commission appoints to do the surveying. What Article V permits is the surveying itself.
Cambodia has cited that article by number in other protests this year, including one on 14 August about survey work at Chouk Chey. Thailand cites it too, pointing the other way.
A Thai foreign ministry briefing of 22 August 2025 records a protest Thailand lodged in September 2017. It objected then to the growth of Cambodian settlement at Ban Nong Chan, to a Cambodian flag raised there and to Cambodian offices opened. Ban is the Thai word for village, and Ban Nong Chan is the Thai-side village the October document pairs with Chouk Chey. Thailand called all of that a breach of its sovereignty and of Article 5 of the same memorandum, which is how Thai texts number it. The briefing places Ban Nong Chan between Pillars 46 and 47, inside the run.
In March 2026 the Thai ministry invoked the article again. It recalled Cambodian construction of a community market, a monument and an administrative building on ground it says is Thai, and said it had protested such things since 2010. That release cited the December statement by paragraph number. In the same document Thailand described its own measures of the period as provisional stabilization, strictly defensive and without prejudice to the survey and demarcation. And it said the survey could not go ahead on the ground, because the border had not stabilised and danger was still posed to the joint survey team.
The survey did start. Thailand’s ministry said the joint team began work between Pillars 42 and 47 on 19 November 2025, and that it was going smoothly. Cambodia’s border secretariat says the work stopped on 8 December, about three weeks in. It has not restarted. Cambodia asked in January for the teams to go back, and Thailand’s answer in March was that the ground was not safe.
The other two places in the protest sit outside all of this. Boeung Trakoun and the ground by the pagoda at O Smach appear nowhere in the October document, which covers the one stretch. That document does not say what covers them.
So the article both ministries reach for permits the surveying, and the surveying is the step that stalled. The adjustment of land occupation waits at the end of a sequence whose second step was never finished, and the two sides have still not said how it would work. What it decides is whether people move. Chouk Chey, Nong Chan, Prey Chan and Nong Ya Kaeo are inhabited places, and the people in them are the subject of the step that comes last.
In August 2002 Thailand asked Cambodia to move the houses at Ban Nong Chan. The Cambodian boundary commissioner of the day answered, by Thailand’s account of that meeting, that any move could follow a check of the precise line between Pillars 46 and 47, and not before. Twenty three years later the two sides wrote that order into a joint document of their own. The check is still not finished.