CIVICUS speaks about the Cambodia–Thailand peace process with Dr Eugene Mark, Fellow and Co-coordinator of the Thailand Studies Programme at the ISEAS –Yusof Ishak Institute, Singapore.

A ceasefire between Cambodia and Thailand was signed on 27 December after weeks of clashes that killed over 100 people and displaced more than half a million civilians, but border tensions have continued. On 6 January, Thailand said a mortar strike wounded a Thai soldier during the ceasefire period, while Cambodia claimed the incident was an operational error. On 9 January, Cambodia’s General Department of Customs and Excise reported that Cambodia–Thailand trade had reached US$3.6 billion, underscoring continued economic interdependence despite the tense situation.

What’s driving the renewed border tensions, and what are the roots of the conflict?

Fighting resumed along the Cambodia–Thailand border in 2025, after a long period of relative calm. The clashes became the deadliest in over a decade, with Thai fighter jets carrying out airstrikes for the first time in years, forcing civilians to flee border areas and creating a humanitarian emergency. Although both sides announced several ceasefires, none brought real stability.

These tensions are rooted in a long-running border dispute that has never been fully settled. The most sensitive area is around the Preah Vihear Temple, an 11th century site with strong symbolic value for both countries, where it’s often linked to sovereignty and national pride.

At the centre of the dispute is a colonial-era mapping problem tied to treaties signed in the early 1900s between Siam – now Thailand – and France, Cambodia’s colonial authority at the time. In 1962, the International Court of Justice ruled that the temple belonged to Cambodia, saying Thailand had implicitly accepted the French map by not challenging it for decades. But the ruling did not clearly define who the surrounding land belonged to. This legal grey area has continued to fuel tensions. When the United Nations Educational, Scientific and Cultural Organization listed the temple as a Cambodian World Heritage Site in 2008, nationalist protests erupted in Thailand. In 2013, the court clarified that most of the surrounding area also belonged to Cambodia and ordered Thai troops to withdraw.

Despite this, large parts of the border remain undefined. Around 196 kilometres are unmarked, and both governments have agreed on only 45 of 74 boundary pillars. This situation allows small incidents to escalate quickly, particularly when domestic politics turn local disputes into national causes.

How stable have the ceasefires been?

After heavy fighting in July 2025, mediation led by Malaysia in connection with the Association of Southeast Asian Nations (ASEAN), supported by China and the USA, produced a truce. During the ASEAN Summit in October 2025, both governments signed the Kuala Lumpur Peace Accord and committed to de-escalation, withdrawing heavy weapons and allowing the deployment of ASEAN observers. But it did not hold. In November, Thailand suspended the agreement and fighting soon resumed.

On 27 December 2025, both sides agreed to another ceasefire that froze troop movements and established an ASEAN Observer Team. This ceasefire also proved fragile, and violence flared again in early January. Although both governments have strong incentives to avoid full-scale war, the ceasefire remains a temporary de-escalation, not stable peace. Domestic political pressure in both countries makes any agreement vulnerable, particularly when leaders fear nationalist backlash if they are perceived as conceding sovereignty.

Economic interdependence can act as a deterrent, but it also adds risks. Cambodia and Thailand share deep trade links, and many livelihoods and supply chains depend on cross-border stability. At the same time, the 2025 crisis showed how easily governments can use these ties as leverage. Cambodia depends heavily on Thailand for electricity, fuel and internet services. During the crisis, Thailand closed border crossings and restricted fuel exports to increase pressure.

What’s the international community doing to prevent further violence?

States and international organisations have stepped up their involvement, turning a bilateral border dispute into a wider regional and geopolitical issue. ASEAN remains the main regional platform, but the crisis has also drawn in major powers, particularly China and the USA, both of which are now playing visible roles in efforts to contain the violence.

Donald Trump intervened directly in last year’s peace efforts and used economic pressure to push both sides back to negotiations. His administration reportedly warned it would not move forward with tariff-reduction talks unless dialogue resumed. At the beginning of the year, the USA also announced a US$45 million aid package focused on border stabilisation, clearing unexploded ordnance and tackling drug trafficking networks and scam operations.

China has taken a quieter but also influential approach. Rather than applying public pressure, it has relied on high-level engagement and its close ties with the Cambodian government and Thai military to steer the situation back into an ASEAN-managed process. It hosted Cambodian and Thai officials in Shanghai in July 2025 and Yunnan in December, positioning itself as a facilitator while supporting ASEAN centrality.

ASEAN is facing a major credibility test. If it cannot manage disputes between its members, external powers will increasingly shape regional outcomes. Although ASEAN’s non-interference principle limited its early response, the bloc later created the ASEAN Observer Team. For it to have tangible impact, however, ASEAN needs to give the mission real authority and technical capacity, including tools to verify incidents and counter disinformation. Otherwise, it will struggle to prevent misunderstandings and stop small incidents from escalating. It will remain just a symbol.

What role has civil society played during this crisis?

The 2025 conflict produced a humanitarian crisis that exceeded the capacity of national authorities to respond quickly and effectively. Civil society organisations stepped in to fill the gaps, delivering emergency food, repairing damaged water systems and creating safe spaces for children and displaced families.

Civil society also played a key protection and advocacy role. It raised concerns about the rights and safety of displaced people and migrant workers caught in the conflict zone and called on both governments to respect international humanitarian law. It issued joint statements demanding an end to the fighting and worked to counter disinformation and nationalist propaganda that were fuelling hostility and narrowing space for dialogue.

What needs to happen next?

Sustainable peace will require technical and political action. Governments must restart and strengthen the Joint Boundary Commission so it can complete border demarcation. Joint survey teams have reportedly resumed work on placing temporary markers in sensitive areas such as Banteay Meanchey and Battambang, but real progress will depend on clear political backing from both governments.

We also need stronger monitoring systems. Without credible ways to track troop movements and prevent misunderstandings, even small incidents can trigger an escalation. A more permanent and better equipped ASEAN Observer Team could help, along with bilateral mechanisms that protect civilians in border areas.

Economic normalisation must follow any security steps. Both governments need to fully implement the Kuala Lumpur Peace Accord, including reopening major border crossings and withdrawing heavy weapons. This would help restore trade, protect livelihoods and rebuild confidence among local communities and investors.

But lasting peace depends above all on political will. Leaders in Cambodia and Thailand must show restraint and stop using nationalist rhetoric for domestic gain. Without this shift, ceasefires will not hold. Reducing political tension is the most important step towards preventing future violence.

CIVICUS interviews a wide range of civil society activists, experts and leaders to gather diverse perspectives on civil society action and current issues for publication on its CIVICUS Lens platform. The views expressed in interviews are the interviewees’ and do not necessarily reflect those of CIVICUS. Publication does not imply endorsement of interviewees or the organisations they represent.