Following a border clash on 28 May at the Chong Bok border pass in Ubon Ratchathani, Cambodia has said that it intends to take its territorial disputes with Thailand to the International Court of Justice, while the Thai government has said that it is committed to bilateral negotiations through the Joint Boundary Commission (JBC) and will not accept the ICJ’s jurisdiction.

With some of the boundary between Thailand and Cambodia still to be demarcated, territorial disputes have been a persistent source of contention between the two countries. Over the decades, there have been several attempts to resolve these border disputes through treaties and bilateral mechanisms, including the Franco-Siamese treaties of 1904 and 1907 and the JBC. But the issue has never been fully resolved.

On 28 May, a clash occurred between Thai and Cambodian soldiers stationed at Chong Bok, after the Thai military reportedly noticed movement of Cambodian troops in the area. Cambodian media reported that one Cambodian soldier was killed.

Get to know Chong Bok and the Ta Muen temple group

Located in Ubon Ratchathani’s Nam Yuen district, the Chong Bok border crossing point is one of the undemarcated points along the Thai-Cambodian border. It is part of the “Emerald Triangle”, a disputed area where the borders of Thailand, Laos and Cambodia meet.

The border crossing has a long history. From 1985 – 1987, it became a battleground between the Thai military and Vietnamese forces, which were occupying Cambodia after toppling the Khmer Rouge in 1979.

Today, it remains a disputed area, along with several other points along the Thai-Cambodian border. These include a complex of three ancient temples: Prasat Ta Muen Thom, Prasat Ta Muen Tot, and Prasat Ta Kwai.

Despite the efforts of various joint border committees, these areas remain disputed due to changes in the natural conditions, damage and removal of some border markers, and the use of different historical maps by both countries.

The Ta Muen temple group is located along the natural watershed that was once agreed to be the border between Thailand and Cambodia. However, natural conditions changed and the flow of water shifted, making difficult to clearly identify the border, leading to overlapping claims.

The damage and removal of demarcation markers over time have also caused technical difficulties in modern border demarcation. The most recent document used to define the modern border is the 1907 Franco-Siamese Treaty which mainly dealt with large-scale swaps of territory between then Siam and French Indochina. The treaty refers to 73 markers along the Thai-Cambodian land border, but these do not cover the entire border, and are placed too far apart to clearly show where the border line runs. Over time, many of these markers have been damaged or removed, which makes it very difficult to use them as a way of clearly marking the border today.

Supalak Ganjanakhundee, an academic and former journalist focusing on ASEAN regional affairs and international relations, said in a 2 June interview with Prachatai that the ongoing disputes also arise from disagreements over the maps used by both sides. The lack of a mutually agreed demarcation, compounded by historical tensions, continues to cause border clashes like the one on 28 May.

What happened at Chong Bok?

On 28 May, there was a skirmish between Thai and Cambodian soldiers at the border. The clash came after two reported attempts by Cambodian troops to dig trenches in the disputed area. Using Thai military sources, The Nation reported that at 5.30 on 28 May, the Thai military dispatched a negotiation team, as the movement of the Cambodian troop violated existing agreements. Due to a misunderstanding, the Cambodian troops opened fire. The Thai troops then returned fire.

The firefight ended after around 10 minutes. Both sides then began negotiations, and the Thai government announced a plan to resolve the territorial dispute by bilateral talks.

However, on 9 June, social media channels of the Royal Thai armed forces posted a 6-minute video with aerial photographs, purporting to prove that between 20 April and 24 May 24, the Cambodian authorities used heavy equipment to cut trees, dig a long trench, set up a “military base” and build a concrete road.

Before the 28 May clash, there had been other incidents in the disputed area around Chong Bok.

On 5 March, the Trimuk Pavilion, built at Chong Bok by Cambodian, Lao and Thai soldiers in 1991, was burned down after a fire spread from a residential area and to the Pavilion, which was under Cambodian administration. No official determination has been made as to whether the fire was accidental or intentional.

The pavilion was built over 30 years ago as a symbol of friendship between Thailand, Laos, and Cambodia. It was designed with three gabled roofs. Inside the pavilion, three Buddha images, one from each country, were enshrined to allow people from all three nations to pay respects and worship, or to rest and relax.

On 2 May, following the Thai-Cambodian General Border Committee (GBC) meeting, Thai Deputy Prime Minister and Defence Minister Phumtham Wechayachai and Cambodian Defence Minister General Tea Seiha held talks to address the ongoing border dispute and agreed to ease tensions. Their discussions focused on reducing the risk of confrontation and avoiding future clashes in areas like Chong Bok and Chong Anma in Ubon Ratchathani where the border is still to be demarcated.

Although a previous Thai-Cambodian agreement called for a 5-kilometre buffer zone, both sides deployed troops in the disputed areas. This led to renewed negotiations, with both parties agreeing to simultaneously withdraw forces to their original positions, in line with the GBC resolution on 1 May.

This was then followed by the first attempt by Cambodian forces to dig trenches and establish a base at Hill 745 in Chong Bok on 18 May. Considering this move a violation of the existing agreement on resolving border disputes called MOU43, the two countries negotiated. The Cambodian military admitted their fault and agreed to stop digging the trenches. Both sides agreed to pull their troops out of the disputed area and planned to arrange a further meeting about joint patrols without weapons.

Supalak said that, in the past two to three months, he noticed attempts to stir up issues regarding the Thai-Cambodian border. It started with the border near Ko Kut in Trat Province, before moving to the Ta Muen temple in Surin, the Trimuk Pavilion in Nam Yuen District of Ubon Ratchathani, and the trench at Chong Bok, which led to a clash.

On 1 June, Phumtham said that the situation following the clash at Chong Bok had eased. Both countries were trying to avoid direct confrontation.

Thailand pushes for bilateral negotiations, while Cambodia insists on going to the ICJ

Following the 28 May clash, the Thai government issued two statements reaffirming its commitment to pursuing a bilateral negotiation in the upcoming JBC meeting on 14 June in Phnom Penh. The first was issued on 4 June, saying that the Thai government intends to resolve the border dispute by peaceful negotiation, in line with with international law and with a commitment to humanitarian principles. The statement clarified that both sides would cooperate to restore the situation to normal and prevent further escalation, while also emphasizing their long-lasting relationship as good neighbours. They agreed to pursue the existing bilateral mechanism to resolve the issue, which is the JBC, as discussed by the Army Commanders of both countries on 29 May.

Meanwhile, the Cambodian government released a statement the same day saying that it has decided to take a case to the International Court of Justice regarding the border disputes in four areas: the Emerald Triangle, Ta Muen Thom Temple, Ta Muen Tot Temple, and Ta Kwai Temple, with or without Thailand’s participation. It will also exclude discussions on these areas from the JBC meeting. Cambodia expressed hope that Thailand would jointly submit the case to the ICJ in the interests of justice, long-lasting friendship, and cooperative relations as neighbours.

On 5 June, the Thai government released its second official statement reiterating that Thailand would address this dispute through bilateral talks and calling on Cambodia to not to raise tensions further.

The statement said that Thailand had tried to avoid unnecessary loss by adopting the already existing bilateral mechanisms: the Joint Boundary Commission (JBC), General Border Committee (GBC), and Regional Border Committee (RBC).

The Thai government’s response to Cambodia’s intention to submit the case to the ICJ noted that Thailand has never accepted the ICJ’s jurisdiction since 1960 and that Cambodia should not complicate the issue further.

The statement emphasized that to prevent unnecessary loss on either side, bilateral talks would be the best solution for both countries as the mechanisms have been clearly progressing in several areas, such as the Thai-Cambodian Friendship Bridge connecting Ban Nong Ian (Sa Kaeo Province) and Stung Bot (Banteay Meanchey Province), and the construction of a new bridge linking Ban Phakkad (Chanthaburi Province) and Phrom (Pailin Province).

It also said that Thailand was ready to participate in the upcoming JBC meeting on 14 June and hoped that Cambodia shared the same commitment to preserve peace, regional stability, and respect for both countries.

Phumtham confirmed that there is nothing to be concerned about, as both sides have maintained their positions and are carrying out their responsibilities. On the ground, military forces remain vigilant, prepared for any circumstance.

The Thai government reassured to the public that it would maintain a close dialogue with Cambodia at all levels, in the spirit of good neighbourly relations and ASEAN unity.

Both sides withdraw troops, agree to weekly talks

Following negotiations between the Thai and Cambodian military, both troops agreed to retreat to the positions originally held in 2024 and hold weekly meetings between military representatives to ease tension. Cambodia also agreed to fill in the trenches dug at Chong Bok.

It was reported on 8 June that Cambodian troops contacted the Suranaree Task Force, the Thai Army’s border defense force stationed along the Thai-Cambodian border, that morning requesting negotiations. Military representatives were sent in after the talk was approved by Army Commander-in-Chief to Gen. Pana Klaewplodthuk.

Phumtham said on the same day that both troops have been conducting joint patrol along the borders. They have agreed to find ways of de-escalating the tension and avoid confrontation, which he said leads to a noticeable improvement in the situation.

He aexpressed his gratitude for the Cambodian government, particularly the Cambodian frontline forces, for engaging in dialogue and contributing to the de-escalation of the situation in accordance with the principles of peace and for the benefit of the people of both countries.

He stated that both sides are looking forward to resolving this border dispute peacefully through the upcoming JBC meeting on 14 June. He urged the public to carefully consider the information they disseminate to avoid creating new conflicts.

The Ministry of Foreign Affairs denies full border closure

The Thai authorities on 6 June began imposing travel restrictions at checkpoints along the Thai-Cambodian borders, including changing the opening and closing times for the entry points and limiting the type of travellers.

Nikorndej Balankura, spokesperson for the Ministry of Foreign Affairs, said that the restrictions were imposed according to a National Security Council resolution made on 6 June. The First Army Region, the Second Army Region, and the Chanthaburi and Trat Border Defense Command have been authorised to implement measures controlling movement across checkpoints along the Thai-Cambodian borders within their respective areas of responsibility.

He said that, contrary to a common misunderstanding, these measures are not a full border closure. Instead, these are measures with steps to be tailored to specific situations in each area:

Step 1 – Limitation on crossings, with the exception of necessary travel, such as for trades, goods transporation, labour, and other essential work, while stepping up on inspections of individuals at risk of being involved in illegal activities;

Step 2 – Reduction of the time period for crossings, including on days and hours for entry

Step 3 – Selective closure of certain checkpoints, such as those in high-risk areas or locations where the situation cannot be adequately controlled.

Step 4 – All checkpoints along the border may be closed, to allow for the highest levels of control.

For example, Nikorndej said, the Aranyaprathet-Poipet checkpoint in Sa Kaeo now remains open from 8.00 – 16.00. Only Thai people crossing the border for tourism or to go to the casinos are prohibited from crossing. And at

He also provided an example of the Aranyaprathet-Poipet border checkpoint in Sa kaeo Province. The checkpoint remains open from 8 a.m. to 4 p.m., with restrictions only on Thai people crossing the border for tourism or gambling purposes. And large vehicles such as six-wheel trucks are still allowed to cross through the checkpoint at the Thai-Cambodian Friendship Bridge.

Nikorndej said that border measures are for the preservation of peace and safety for both countries. He said that the Thai government took into consideration border trade, livelihood, and humanitarian concerns, and that it has tried to ensure that these measures would not affect civilians. Travel restrictions are tailored for each checkpoint. Routine and essential crossing, such as for trade, education, medical services, and labour are still permitted.

He reiterated that Thailand is ready to pursue the negotiations through bilateral mechanisms, especially in the upcoming JBC meeting this Saturday (14 June). The Thai government would continue to adhere to MOU43, an agreement on survey and demarcation of land boundaries between Thailand and Cambodia, which serves as a legal framework for resolving land disputes between the two countries. It believes that using existing bilateral mechanisms would ease tension. Thailand therefore calls on Cambodia to make use of these existing mechanisms to ease tension and prevent further complications.