Ceasefire. The recent border clashes between Thailand and Cambodia mark yet another episode in the protracted and unresolved territorial dispute rooted in ambiguous colonial cartography, disputed heritage, and strong national pride. Tensions intensified earlier this year when in February 2025, Cambodian troops were reported singing their national anthem at the Prasat Ta Moan Thom site which prompted a Thai police response. In May, a Cambodian soldier was killed near the Chang Bok area. By July, a full-fledged artillery exchange erupted, prompting the displacement of over 200,000 civilians and the death of at least 35 people. Emergency meetings were convened at the United Nations Security Council (UNSC), which led to reference of the matter to regional mechanisms. With intervention from the Association of Southeast Asian Nations (ASEAN), a ceasefire was negotiated—facilitated by Malaysia, the current ASEAN Chair, with reported parallel involvement from the United States and China. Limits of traditional international adjudication. Supporters of the traditional liberal post-World War II system of international adjudication could argue that this border dispute illustrates the importance of the adjudication of the International Court of Justice (ICJ). At the heart of the dispute lies the Preah Vihear temple complex, a Hindu shrine of considerable civilisational significance situated atop the Dangrek Mountains. While the 1908 map prepared under the Franco-Siamese agreement demarcated the site within Cambodian territory, the Thai government has long contested this claim, particularly in relation to the 4.6 square kilometres of land surrounding the temple. In 1954, Thai forces occupied the temple, prompting Cambodia to approach the ICJ. The ICJ’s 1962 ruling declared Preah Vihear to be within Cambodian sovereignty and ordered Thailand to withdraw its troops. Crucially, the court held that Thailand’s prior acceptance of the colonial-era maps, when France controlled Cambodia, amounted to tacit recognition of the boundary. Nevertheless, ambiguity persisted regarding adjacent territory. Many post-colonial conflicts have their origin in ambiguities of colonial era boundary delimitation. In this case, the boundary line did not conform to the watershed line at all points. This was further compounded by differing cartographic methodologies: Cambodia has consistently referred to the 1:200,000 scale map, while Thailand favours a 1:50,000 scale. To address this, both states signed a Memorandum of Understanding in 2000 establishing a Joint Border Committee (JBC), tasked with finalising land delimitation. The dispute re-escalated in 2008, following Cambodia’s nomination of the Preah Vihear temple as a UNESCO World Heritage Site. Thailand objected, citing unresolved sovereignty over the surrounding land. Domestic political dynamics elevated the temple into a symbol of national pride, triggering the first significant military confrontation in decades. Armed exchanges continued intermittently until 2011. Cambodia once again approached the ICJ, seeking clarification. The court, in 2013, reaffirmed that not only the temple, but also its immediate vicinity, belonged to Cambodia. Despite these rulings, Thailand has resisted ICJ’s ruling, having not submitted to its compulsory jurisdiction. Cambodia on the other hand, applied for ICJ adjudication on four additional disputed sites in June 2025. This has been met with strong resistance from Thailand, which insists on bilateral resolution.

Cambodia is of course entitled to seek international adjudication. The ICJ is also entitled by way of international law doctrine to enshrine a kind of estoppel on Thailand’s claims, given colonial era agreements. However, legal permissibility and doctrine is confronted with the limits of the effectiveness of ICJ jurisdiction where the militarily and economically weaker country resorts to international adjudication in the face of preference for bilateral resolution by the other country. This need not always be so, as was illustrated by India’s acceptance of an international award over a maritime boundary with Bangladesh. However, the reality of realpolitik between two neighbours of unequal strength can often render international adjudication infructuous.

Rise of regional mechanisms backed by economic leverage. The latest ceasefire has clearly brought a temporary halt to hostilities. Given the limits to traditional international adjudication, is this a triumph of regional cooperation mechanisms given the abdication of responsibility and even paralysis in decision making by the vaunted permanent members (P5) of the United Nations Security Council (UNSC)? Taking the Thai-Cambodian border dispute as an example, does the current geopolitical churn allow for the resolution of long-standing disputes through regional mechanisms? Do the structural problems of the post- World War II international adjudication mean that the future to resolution of border disputes lies with the mailed fist of coercive economic power (be it trade or sanctions) behind the velvet glove of regional mechanisms?

First, despite the apparent attractiveness of the above theory, it may understate the importance of regional mechanisms. Whilst ASEAN is characterized by consensus based decision making, which is often slow and ponderous, ASEAN’s Chair Malaysia was quickly able to offer Kuala Lumpur as a neutral venue for both Prime Ministers of Thailand and Cambodia to travel to and reach a ceasefire agreement. Since then, it has been announced that Kuala Lumpur will be the venue for border talks between the two sides.

Second, notwithstanding the undoubted economic leverage of the two P5 members involved – the US and China — having diplomatic pressures that are transactional and conditional (such as US threats on trade), may not offer the kind of patient leverage that real resolution of long standing colonial era boundary disputes require. At the same time a trust deficit may undermine China’s position, given Beijing’s entrenched economic interests and strategic investments in Cambodia.

A third civilizational pathway. Perhaps there is a third way rooted in the long-standing civilizational traditions of the region. Thailand and Cambodia have civilisational ties rooted in religion, language and cultural traditions. As part of an effort to preserve such civilizational ties, India has invested substantially in the conservation of sacred sites in Southeast Asia, including Angkor Wat and other sites in Cambodia such as Ta Prohm Temple and crucially, the Preah Vihear temple. The UNESCO International Coordinating Committee (ICC) for Preah Vihear is co-chaired by India and China. Moreover, the Archaeological Survey of India has committed USD 5.5 million for the temple’s restoration over the next decade.

Consequently, under the aegis of UNESCO, countries with civilizational ties could use heritage diplomacy to foster an international cross border heritage site, which would serve the interests of both Cambodia and Thailand. Such an approach could be considered in the ongoing bilateral process between Thailand and Cambodia. This could open up the rather remote area on both sides of the border to tourism and economic development.

Some may argue that civilizational heritage may represent the past but economic power represents the future. Ultimately, this conflict shows that ceasefires through regional mechanisms backed by economic power may pause a conflict. However, durable peace may require creative diplomacy founded on long standing heritage and civilizational ties.