What is unfolding along the Thailand–Cambodia border is neither a collapse of diplomacy nor a path to settlement, but a managed cycle of instability in which both, ceasefires and use of limited force coexist between two sovereigns. Understanding why this cyclical pattern of conflict recurs requires a need to move beyond immediate triggers and gauge the structural politics of the frontier itself along with its colonial past. Writes Deepanshu Mohan**

In late December 2025, Thailand and Cambodia agreed to yet another ceasefire after weeks of intense fighting along their disputed border. The agreement followed nearly twenty days of clashes which left more than a hundred people dead and forced over half a million civilians to flee their homes, according to humanitarian reporting. Artillery exchanges, rocket fire, and air operations marked one of the most serious escalations in tensions between the two neighbouring countries in years.

The truce was framed as an extension of the Kuala Lumpur Peace Accord, signed in October 2025 under external mediation, which sought to stabilise the frontier through demilitarisation and confidence-building measures.

Its durability, however, was tested immediately.

In early January 2026, a Thai soldier was wounded by Cambodian mortar fire during the ceasefire period. Phnom Penh described the incident as an operational error, while Bangkok issued warnings but stopped short of abandoning the agreement.

What is unfolding along the Thailand–Cambodia border is neither a collapse of diplomacy nor a path to settlement, but a managed cycle of instability in which ceasefires and limited force coexist.

A Flashpoint That Keeps Evolving, Not Resolving Itself

The January incident was not an anomaly. It was the latest episode in an escalation cycle that took shape in mid-2025. A skirmish near Chong Bok earlier that year resulted in the death of a Cambodian soldier, followed by the wounding of Thai troops by landmines in the same contested area. By July, the confrontation widened, with Thailand launching retaliatory airstrikes and both sides mobilising forces along multiple stretches of the border.

Reporting by the United Nations documents the use of heavier weaponry, including rocket systems and combat aircraft, alongside mass civilian displacement across border provinces. Diplomatic interventions punctuated this cycle but failed to arrest it.

July mediation efforts brokered with the involvement of the United States, China, and Malaysia collapsed within weeks amid mutual accusations and the absence of credible enforcement.

The October Peace Accord promised demilitarization but offered little in the way of binding compliance. The December truce froze active hostilities, as it left intact the incentives that had driven escalation in the first place.

Understanding why this cyclical pattern of conflict recurs requires moving beyond immediate triggers to the structural politics of the frontier itself. The roughly 800-kilometre Thailand–Cambodia border is a colonial construct shaped by the Franco-Siamese treaties of 1904 and 1907, with disputes around sites such as Preah Vihear and Ta Muen Thom carrying enduring symbolic weight.

While International Court of Justice rulings clarified sovereignty, they failed to depoliticise the frontier, leaving history less a cause of conflict than a resource repeatedly mobilised for contemporary political leverage.

Thailand’s Side: Sovereignty, Security Narratives, and Electoral Utility

For Thai governments, the contested border with Cambodia has long functioned as a reliable site for asserting sovereignty during domestic uncertainty. The December 2025 escalation coincided with leadership instability and civil–military strain, making firmness vis-à-vis Cambodia a low-cost signal of sovereign authority incentivising Thai movement along the border.

This vulnerability was exposed months earlier. On 18 June 2025, a leaked phone call between then prime minister Paetongtarn Shinawatra and former Cambodian leader Hun Sen suggested a breakdown in civilian authority over border commanders at a moment of rising tension.

The political fallout was swift: more than 20,000 protesters rallied in Bangkok, the Bhumjaithai Party withdrew from the governing coalition.

What followed were legal petitions alleging ethical and national security violations leading to Paetongtarn’s removal from office within weeks. Her successor, Anutin Charnvirakul, assumed office on a platform centred on restoring sovereign resolve, dissolving parliament on 12 December 2025 amidst active air operations near Poipet and effectively synchronising military escalation with electoral positioning ahead of the February 2026 polls.

What distinguishes the current escalation cycle is the expansion of Thailand’s justificatory framing of its use of force. From early December 2025, military deployment operations were presented not only as responses to territorial violations but as efforts to dismantle industrial-scale scam centres in Cambodian border provinces.

Airstrikes and artillery targeted sites in Poipet, Banteay Meanchey, and Bavet long linked to casino economies such as O’Smach resort, online fraud, human trafficking, illicit finance, and alleged military purposes. This reframing embedded territorial escalation within a broader transnational security narrative centred on cybercrime and organised criminal networks.

The political utility of this approach was significant. It justified airpower, artillery, and counter-rocket fire as clashes intensified.

By mid-December 2025, at least 15 Thai soldiers were killed, civilians died in Sisaket and Surin, and evacuations exceeded 400,000 people on Thailand’s side. Framing operations as counter-crime measures limited the diplomatic backlash and sustained external engagement. The resulting is managed escalation, wherein sovereignty claims and transnational security narratives reinforce political legitimacy while leaving instability intact.

Cambodia’s Side: Regime Legitimacy, Strategic Asymmetry, and Diplomatic Pushback

During the December 2025 escalation, Cambodia’s leadership adopted a de-escalatory public image even at moments of intense tension. Yet this restraint did not emerge in a vacuum. The pattern began earlier: on July 25, the Royal Thai Air Force deployed F-16s in two waves, striking Cambodian military positions near Preah Vihear Temple, Ta Muen Thom, and Phu Makua.

Four jets hit two targets at noon and two more struck additional targets later that afternoon, with Thailand claiming these were firing bases used to attack Thai civilian homes and hospitals. This escalation set the stage for Cambodia’s subsequent diplomatic strategy. Deputy Prime Minister Sun’s call to “lower the temperature” was a posture that functioned as a diplomatic strategy aimed at reassuring domestic elites and foreign investors. This diplomatic restraint unfolded alongside active Thai military operations.

Cambodia’s trade with the US reached $13.5 billion in 2024, while China’s exports to Cambodia totalled $15.33 billion in the same year. China represents 43% of Cambodia’s FDI inflows, with foreign direct investment accounting for 13.5% of GDP as of 2019, significantly higher than Thailand’s 1.1%.

Against this backdrop, diplomatic restraint can be viewed as a signal directed as much at Washington and Beijing as at Bangkok. By projecting itself as the stabilising actor, Phnom Penh seeks to reassure its principal economic partners that it will not become a source of regional disruption, while implicitly shifting responsibility for renewed instability onto Thailand.

As Bangkok expanded its justificatory framing of the use of force, Phnom Penh moved to narrow it, directly contesting the use of ‘anti-scam’ narratives to legitimise cross-border strikes. By rejecting Thailand’s claim that scam centres justified military action, Phnom Penh sought to prevent law-enforcement narratives from legitimising cross-border force.

Phnom Penh has accepted ceasefire arrangements while avoiding language that could be read as retroactively endorsing Thailand’s military actions. As active hostilities have eased, contestation has increasingly shifted to official statements and diplomatic exchanges.

Violations are masked under defensive operational errors or miscommunication, which preserves the foundation of the ceasefire while simultaneously refusing to concede that Thai operations were justified or proportionate. Cambodia continues to demand that Thailand withdraw from the disputed areas, favouring boundary commissions and international legal mechanisms over military pressure.

External Geopolitical Dynamics: Mediation, Leverage, and Transactional Peace

External powers have actively shaped the latest Thailand–Cambodia border crisis, seeking to stabilise the frontier but without altering the domestic incentives that drive recurrent escalation. In January 2026, the United States announced a $45 million aid package to support implementation of the Kuala Lumpur Peace Accords, a ceasefire framework agreed in October 2025 under U.S. and Malaysian auspices.

According to U.S. officials, the funding includes $15 million for border stabilisation and displaced persons’ support, $10 million for demining and unexploded ordnance clearance, and $20 million for anti-scam, drug-trafficking and transnational crime initiatives. This assistance follows intense clashes in July and December 2025 that killed at least 101 people and displaced over half a million civilians on both sides of the frontier, with artillery barrages, fighter-jet sorties, and rocket exchanges reported along sectors of the 800-kilometre border.

China has also sought to cast itself as a stabilising actor. Beijing confirmed that the December truce was being “gradually implemented,” noting Thailand’s return of eighteen Cambodian soldiers as a confidence-building step. The Chinese foreign ministry publicly expressed hope that the ceasefire would be “comprehensive and lasting,” signalling Beijing’s interest in a peaceful outcome.

Yet much of this engagement is transactional. ASEAN has largely followed the conflict rather than shaping it. Observer deployments and mediation arrive after violence, constrained by consensus rules that limit enforcement and leave escalation incentives untouched. Aid disbursement and diplomatic traffic follow moments of crisis without embedding mechanisms that address domestic incentives that drive renewed escalation.

On The Way Forward

The civilian cost has been severe yet politically contained. By mid-December 2025, Cambodian authorities reported 518,611 people displaced by artillery, rocket fire and Thai F-16 airstrikes, while Thai officials acknowledged around 400,000 evacuees across eight border provinces.

Fighting around crossings such as Poipet left up to 6,000 Thai citizens stranded after Cambodia closed checkpoints, disrupting labour mobility and informal trade. Markets, schools and hospitals across Sisaket, Surin, Oddar Meanchey and Banteay Meanchey were repeatedly shut, agriculture near the artillery range was abandoned, and tourism hubs suffered abrupt demand shocks, affecting investors and production networks tied to regional connectivity.

Durable de-escalation would require shifting escalation management away from military signalling and towards shared civilian mechanisms. Joint civilian border structures involving local authorities, community leaders, and other elements of civil society could manage the essential cooperation, such as evacuation protocols, incident logging and rapid clarification of alleged violations. Independent monitoring of buffer zones would also help in narrowing down the space for fabricated claims and tactical ambiguity.

However, these measures do not signal progress toward settlement. They constitute a conflict-response architecture — protocols for border closures, labour movement, evacuation, and incident clarification — designed to absorb shocks rather than prevent escalation. They function as buffers, not bridges.

Finally, legal and technical demarcation would not resolve the dispute, but it could provide a platform for structured engagement through joint mapping, transparent cartography, and incremental reference to past ICJ rulings. Such processes would not eliminate nationalist claims, but they could channel contestation into procedural arenas rather than military ones.

*The views expressed in the blog are those of the author alone. They do not reflect the position of the Saw Swee Hock Southeast Asia Centre, nor that of the London School of Economics and Political Science.

**Saksham Raj, Aditi Lazarus & Simar Kaur, as researchers from Centre for New Economics Studies (CNES) also contributed to this column.

***Banner photo by Bram Wouters on Unsplash

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