Conflict Weekly 300th Issue

CWA # 1812
Conflict Weekly 300th Issue
Thailand–Cambodia border conflict: History, Politics, Cost and Regional Mediation
China, East Asia and Southeast Asia
Conflict Weekly 300, 25 September 2025, Vol 6, No. 38

Kasvi Batra
25 September 2025

Photo Source: Reuters

The 2025 Thai–Cambodia border conflict escalated sharply after several incidents. Tensions began on 13 February when Thai soldiers blocked Cambodian tourists from singing their national anthem at Prasat Ta Muen Thom. A clash on 28 May at Chong Bok killed a Cambodian soldier, prompting Cambodia to consider approaching the ICJ while Thailand favored bilateral talks. From 5–29 June, meetings between representatives from both the countries sought to contain escalation. Amid this fragile calm, PM Paetongtarn Shinawatra’s private call to Hun Sen, labeling Lt Gen Boonsin Padklang as “aligned with the other side” was leaked, triggering outrage and her subsequent suspension and removal. On 16 July, a landmine at Chong Bok injured three Thai soldiers, leading to accusations against Cambodia, border closures, and Thai F-16 airstrikes reportedly using cluster munitions. Malaysian PM Anwar Ibrahim convened ASEAN-backed talks, supported by the US and China, leading to a ceasefire on 28 July and a China-brokered reaffirmation in Shanghai on 30 July.

1. Remnants of colonial history
The Thailand-Cambodia border conflict stems from colonial-era mapping inconsistencies; specifically, a mismatch between the 1904 Franco-Siamese treaty, which set the boundary along the watershed line, and a 1907 French-drawn map placing Preah Vihear on the Cambodian side, despite it lying north of the watershed. In 1953, post-independence Cambodia deployed troops to Preah Vihear to assert sovereignty, prompting Thai protests. In 1959 after failed talks, Cambodia took the dispute to the International Court of Justice (ICJ). In 1962, the ICJ ruled the Preah Vihear Temple belonged to Cambodia, citing Thailand’s decades-long acceptance of the 1907 map as binding. After the ICJ ruling, Thailand complied by withdrawing its troops, but continued to contest the surrounding 4.6 sq km area, which was not addressed in the judgment. In 2008, tensions flared after UNESCO listed the Preah Vihear Temple as a World Heritage Site under Cambodia’s application, sparking widespread protests in Thailand. In 2013, the International Court of Justice  affirmed Cambodia’s sovereignty over the Preah Vihear Temple and its entire promontory, ordering Thailand to withdraw all security forces to resolve lingering ambiguities.

2. Internal politics of Thailand and Cambodia 
The 2025 border clashes triggered political upheaval in Thailand. Paetongtarn Shinawatra’s leaked call, in which she referred to Hun Sen as “uncle” and disparaged a Thai military commander, fueled public sympathy for the armed forces and conservatives long opposed to her family. The scandal upended her party Pheu Thai’s coalition with Bhumjaithai, initially brokered with establishment backing to exclude the reformist Move Forward Party, collapsing as Bhumjaithai leader Anutin Charnvirakul assumed the premiership with opposition support. The episode highlighted the enduring influence of Thailand’s conservative establishment, ended backchannel diplomacy between the Hun Sen and Shinawatra families, and prompted martial law in northeastern districts during the conflict, deepening civil–military mistrust.

In Cambodia, the conflict reinforced centralized authority as Hun Sen reasserted dominance over PM Hun Manet. It bolstered domestic legitimacy, projected nationalism, strengthened Cambodia’s negotiating position with Thailand, and highlighted alignment with China. The crisis also enabled the leadership to divert attention from economic pressures, U.S. trade sanctions, and transnational crime.

3. The Human and economic cost of the conflict
The conflict resulted in significant human and economic impacts. Over 130,000 Thai civilians were displaced, and at least 19 individuals, including civilians and soldiers, were killed. Thousands of Cambodian migrant workers were expelled from Thailand, facing economic hardship. The conflict also disrupted cross-border trade, with Thailand's exports to Cambodia, valued at USD 10.4 billion in 2024, facing severe disruptions. Additionally, the UNESCO-listed Preah Vihear temple became militarized causing damage to the site. 

4. Role of the ASEAN 
The ceasefire marks a rare success for ASEAN-led diplomacy, offering a platform for dialogue amid criticism over its inaction on other regional crises. However, it also exposes ASEAN’s reliance on external pressure and strong chairmanship, rather than institutional strength. The bloc lacks enforcement tools like a peacekeeping force or monitoring mechanisms, and past proposals such as Indonesia’s 2011 observer mission were rejected due to sovereignty concerns, hindering effective implementation. Mediating the ceasefire enhanced Malaysia’s diplomatic profile, reaffirmed its  centrality in ASEAN, and boosted Anwar Ibrahim’s statesman image, positioning the country as a credible regional mediator. The ceasefire may enhance ASEAN’s credibility in managing regional disputes, but recurring border clashes highlight the need for stronger conflict management mechanisms beyond ad hoc diplomacy.

5. The US and China backing the ASEAN
A key feature of the Thailand-Cambodia border conflict was the rare external involvement of both the US and China in backing ASEAN-led mediation. For Washington the intervention reflected strategic imperatives as Thailand remains a key-treaty ally and preserving stability along its borders is central to US’ Indo-pacific strategy. During the conflict, Trump threatened to withhold trade agreements, a move that accelerated the ceasefire while allowing the US to counter China’s growing influence in the Mekong sub-region.

For Beijing, prolonged instability threatened major BRI projects in mainland Southeast Asia. Cambodia’s reliance on China evident in ventures like the Sihanoukville SEZ and its consistent support for Beijing’s South China Sea claims made Chinese backing expected. More notable was China’s deeper engagement with Thailand, a traditional US  partner, underscoring its growing sway. By brokering the ceasefire reaffirmation in Shanghai, China has projected itself as a guarantor of stability and cooperative actor with ASEAN and Washington. While external involvement secured the truce, it also risks complicating regional politics and entrenching great power competition.

What Next?
Since the ceasefire, the conflict has entered a state of restive calm. Within days, Thailand accused Cambodian troops of multiple truce violations, underscoring lingering mistrust. To stabilize the situation, both sides agreed in early August to allow ASEAN observers to monitor the ceasefire, followed by Malaysia-hosted talks to develop permanent border management guidelines. By late September, Thailand’s new foreign minister pressed for troop reductions and mine clearance, reflecting cautious progress. Yet occasional flare-ups and protests in contested areas highlight the truce’s fragility and the risk of renewed tensions.

About the author
Kasvi Batra is an independent scholar based in Bangalore.

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