Thailand-Cambodia Conflict: ASEAN’s Structural Limits Revealed

A special meeting of the ASEAN foreign ministers, urgently convened on 22 December 2025 in Kuala Lumpur under Malaysian presidency, once again exposed the glaring weaknesses of regional consensus in the face of a border conflict that has already displaced more than 900,000 people and caused dozens of casualties on both sides.

he ASEAN foreign ministers’ meeting took place in Malaysia on December 22

While Phnom Penh is calling for firm mediation, Bangkok maintains an inflexible stance, retaining a clear strategic and military advantage that paralyzes any rapid resolution. This escalation — the most serious since 2011 — deeply calls into question the power dynamics within Southeast Asia.

Recent Escalation and Human Toll

Since 8 December 2025, exchanges of artillery and small arms fire have surged again along the contested 817-kilometer border. Phnom Penh reports 518,611 internally displaced people and 19 soldiers killed, while Bangkok counts 400,000 displaced and 22 fatalities, with both sides accusing each other of incursions and disproportionate use of force near sensitive sites such as Preah Vihear and Mom Bei.

This flare-up follows an October ceasefire — imposed under U.S. pressure — that held for only two months, underscoring the chronic instability of the dispute despite bilateral rounds through the Joint Border Committee.

Structural Limits of ASEAN Exposed

ASEAN — pillar of “non-interference consensus” — now confronts its own foundations: the principle of non-interference and the absence of binding sanctions. The meeting, delayed from 16 to 22 December due to internal disagreements, brought together all 11 members — including Timor-Leste as an observer — around satellite imagery provided by the United States, resulting only in calls for “bilateral dialogue” and “restraint.”

Historically, crises such as the Cambodian blockade on Philippine claims in the South China Sea in 2016 have shown how a single veto can torpedo unity, opening the door to extra-regional influences such as China or the United States. As mediator, Kuala Lumpur struggles to impose more than symbolic frameworks, risking prolonged talks with no concrete progress even into Christmas.

Thailand’s Strategy: Tough Pragmatism and Military Advantage

Thailand has adopted a resolutely offensive posture, rooted in a sophisticated geopolitical calculation that explains its control over the dispute. With better-equipped forces — modern artillery brigades and air superiority — the Royal Thai forces have retaken positions such as Mom Bei, categorically rejecting the jurisdiction of the International Court of Justice (ICJ), which ruled in Cambodia’s favor in 1962 regarding Preah Vihear.

Thai Foreign Minister Don Pramudwinai described the October agreement as “too rushed to please Donald Trump,” while maintaining what he calls “legitimate defensive operations” against supposed “Khmer provocations.”

This nationalist rhetoric, amplified by a heated media environment in Bangkok, serves a domestic agenda: under pressure from ultranationalists, the conservative government bolsters its popularity by projecting strength against a neighbor seen as vengeful.

Economically dominant — border trade with Cambodia amounts to roughly $10 billion annually — Bangkok knows that Phnom Penh depends on its markets for agricultural and textile exports, implicitly using this asymmetry as leverage.

Diplomatically, Thailand also cultivates solid bilateral alliances with Vietnam and Laos, attempting to isolate Cambodia within ASEAN while flirting with Washington to counter Chinese influence in Phnom Penh.

Geopolitical Stakes: Sino-American Rivalries and Regional Fragility

This conflict is more than a bilateral quarrel; it crystallizes Sino-American tensions in Southeast Asia. Former U.S. President Donald Trump had forced a ceasefire in October through economic pressure on Bangkok, but Beijing is now timidly engaging in mediation efforts. Meanwhile, the European Union and the United Nations are calling for de-escalation, while NGOs like Human Rights Watch denounce potential violations of international humanitarian law.

For ASEAN, failing to impose a monitored ceasefire risks eroding its credibility, favoring alternatives such as the Quad or AUKUS.

Uncertain Outlook and Lessons for Phnom Penh

Without mechanisms to enforce a ceasefire, cycles of violence are likely to continue. Cambodia may need to diversify its alliances — toward Hanoi or Singapore — and return to the ICJ to re-legitimize its claims. Thailand, commanding the tempo of events, will set terms as long as it retains its strategic edge.

Ultimately, this crisis reveals a Southeast Asia where regional diplomacy yields to bilateral power dynamics, threatening the stability of a zone vital to global commerce. Phnom Penh pays the price as Bangkok consolidates its frontier hegemony.