Written by: Jonathan Jordan Staff of Research and Development

On Tuesday, 24th of July 2025, the seemingly peaceful region of Southeast Asia was perturbed by an orchestra of artillery, missiles, and small arms fire. The conductors, Thailand and Cambodia, opened fire on each other in an unprecedented show of modern interstate violence among ASEAN members. What had started as the death of a Cambodian soldier near Preah Vihear—a contested Hindu temple—quickly deteriorated into open conflict that lasted days (Muhammad, 2025). Thankfully, due to the efforts of Malaysia’s Prime Minister Anwar Ibrahim, the United States, and China, a ceasefire agreement was reached on July 28th (Suhenda & Tanamal, 2025). All seems well then, right?

Image 1. Acting Prime Minister Phumtham Wechayachai of Thailand (left) and President Hun Manet of Cambodia shake hands with Prime Minister Anwar Ibrahim between them after talks on a ceasefire in Putrajaya, Malaysia, on July 28th 2025.
Source: AFP/Mohd Rasfan

To the contrary, the events that have transpired raises a few questions. One of them is regarding ASEAN’s role in the region’s peacebuilding efforts. The ASEAN Way specifically underlines the principle of non-intervention and consensus-based decision-making. However, is this really the best for regional security? This article argues that while ASEAN has done a great work in maintaining regional stability, it still needs to tackle its own weaknesses in the same area by examining the history of the Thai-Cambodian conflict and evaluating ASEAN’s efforts to solve it.

Generational Bloodshed at Preah Vihear
Before the foundation of Ayutthaya, a Thai dynasty, in 1351, the peoples of Thailand and Cambodia constantly interacted culturally and economically (Kasetsiri et al., 2013). This is reflected in both countries’ similar cultures and languages. The predecessor of the Ayutthaya Kingdom—Sukkothai—was even part of Angkor, predecessor of modern-day Cambodia, mandala, a political system in pre-colonial Southeast Asia in which multiple monarchs radiate circles of influence and dominate smaller, less powerful kingdoms, and looked up to it (Acharya, 1999). However, Angkor’s power deteriorated, and Ayutthaya invaded it in 1431, rendering it into a vassal state under Ayutthaya’s own mandala. This is the start of animosity towards each other.

Since then, Thailand and Cambodia have had a love-hate relationship. Cambodia, threatened by Thai and Vietnamese dominance, tried to ensure its own survival via hedging between the two regional powers and even once rebelled against Ayutthaya when they were busy fighting Myanmar (Kasetsiri et al., 2013). The constant fight for survival led King Noronom of Cambodia to agree to be a French protectorate in 1863. Eventually, pressure from colonial powers resulted in Thailand conceding some of its territories to France, including western parts of what now constitutes Cambodia.

This humiliation at the hands of foreign powers contributed to disputes of the border frontiers of Thailand and Cambodia, such as that occurring in Preah Vihear. Preah Vihear is an ancient Hindu Temple built by Angkor. Although not as big as Angkor Wat, Preah Vihear still has architectural, archaeological, and religious significance as a temple built to resemble the sanctuary of Shiva and other Hindu gods (Oliver, 1962; Borell 2013). The fact that it still is a place for pilgrimage to Buddhist worshipers as well and that it was built by a predecessor of Cambodia made the Hindu temple located near the border a contested zone, especially as Cambodia and Thailand were grappling with ideas of nationalism in the 20th century—trying to find an identity. 

After the Second World War, contested claims of the Preah Vihear surfaced due to Thai perception of lost territories to unfair imperialism at the hands of France and now the newly-independent Cambodia. In 1962, both countries took the dispute to the International Court of Justice, resulting in the court ruling in favor of Cambodia (Kasetsiri et al., 2013). This ruling—rejected by Thailand—fueled more tension between the two nations, which was exacerbated by Thailand’s support of Pol Pot’s Khmer Rouge during the Cambodian-Vietnam War to create a buffer between it and Vietnam.

With the turn of the millennium, the contest for Preah Vihear devolved into violence and armed conflict. In 2008, open conflict broke out because of Cambodia nominating the Preah Vihear Temple as a UNESCO World Heritage, which managed to be mediated in 2011 (BBC, 2011; Sothirak, 2013). However, over a decade later, bullets and shells were exchanged at the border in the deadliest conflict between the two neighbors in recent times, resulting in over 40 deaths and more than 300,000 people seeking refuge (AFP, 2025).

In addition, nationalism is a complicating factor in both Southeast Asian states’ relations. One characteristic of Asia is that there is a strong presence of state-centered norms as opposed to the more individualistic, liberal values of the West (Pekkanen et al., 2014). Much like in other Asian nations, in Cambodia’s and Thailand’s case, nationalism is an extension of this state-centered idea in order to find an identity in a post-colonial system. Sentiments of nationalism are often misused by Thai and Cambodian leaders in order to further their own interests, sowing seeds of mutual distrust with a force meant to unite (Kasetsiri et al., 2013). Hatred among the common people of both nations against each other still persists, with Cambodians in Thailand facing targeted attacks and discrimination (Ratcliffe & Siradapuvadol, 2025).

Where Is ASEAN?
Different approaches to settling the Thai-Cambodian border dispute have been attempted before. Bilaterally, Thailand and Cambodia established the Joint Boundary Commission (JBC) in 2000 to demarcate the Thai-Cambodian border (Kasetsiri et al., 2013). However, technical problems along with incidents that worsened relations halted the commission’s work. Thailand has insisted the Preah Vihear dispute be settled bilaterally. On the contrary, Cambodia is reluctant since it recognizes the ICJ ruling of 1962, and since Thailand would be in a superior position in a bilateral context due to the tendency of bilateralism to reflect distribution of power, which Thailand has more of in this case (Wright, 2018).

This leaves institutions, such as ASEAN, as the most likely candidate to be a mediating third party. So, where has ASEAN been in all of this? Unfortunately, ASEAN has not done much to resolve the dispute. During the 2008-2011 conflict, ASEAN tried to settle the matter through informal meetings and agreements, resulting in the truce in December of 2011 (Kasetsiri et al., 2013). However, the ceasefire was not followed up by serious actions to tackle the root of the problem. The problem was only swept under the rug. And that inaction resulted in another catastrophic conflict more than a decade later.

Although Malaysia, the current chairman of ASEAN, was able to broker a ceasefire, a lasting peace seems unrealistic. The current plan is for ASEAN observers to inspect the border and to hold more talks under the General Border Committee (GBC) that would hopefully end the issue (Nachemson, 2025; Reuters, 2025a). However, continued mutual distrust and border incidents have undermined these efforts. Cambodia and Thailand repeatedly accused each other of violating the ceasefire.

Military build-ups keep happening on both sides, and refugees are still not allowed to return to their homes amid fears of resurging violence. On July 30th, Thailand claimed Cambodia launched an overnight attack, and three Thai soldiers were injured by a landmine on the disputed territory (AFP, 2025; Reuters, 2025b). This is not permanent peace, but a mere fragile temporary truce, just like the 2011 agreement.

Image 2. Displaced children in Mueng Det, Thailand, being taught lessons by volunteers at an evacuation centre on August 5, 2025.
Source: Al Jazeera/Andrew Nachemson

The Thai-Cambodian conflict is only one of numerous ongoing tensions and disputes occurring among and in ASEAN member states. The South China Sea issue is not going away anytime soon. Overlapping claims between Brunei, Malaysia, Vietnam, and the Philippines have caused mounting tensions due to numerous incidents (Villamor, 2017). The involvement of China via its nine-dash line further complicates matters, inciting conflict with ASEAN nations, especially the Philippines, with a recent clash damaging a Chinese coast guard vessel (Agencies, 2025). Meanwhile, disputes over the Ambalat waters between Malaysia and Indonesia rose up, and the five-point consensus still has not had an effect on Myanmar’s civil war (Reuters, 2025c; Uli, 2025). To top it off, threats of reciprocal tariffs under Trump have pitted ASEAN nations against each other as they individually sought to secure their national interests (Juwita, 2025). 

Disputes, conflicts, and disunity have affected stability in the region, and the recent Thai-Cambodian only have added more fuel to the fire. It has only highlighted ASEAN’s repetitive failures in conflict resolution. These issues show ASEAN’s difficulty to unite in a short period and its lack of effectiveness in resolving regional security issues that have been plaguing it for years with the potential of open conflict and wider distrust not out of the question.

What Can Be Done?
ASEAN’s lack of strong action in handling its members’ own conflicts and its more fragmented nature is due to its status as a relational multilateral organization. Qin Yaqing (2019) defines relational multilateralism as a type of multilateral cooperation that relies on positive relations for its governance. This means that for ASEAN, the most important element is the maintenance of good relations among its members, even at the cost of institutional-building. This focus manifests itself in the ASEAN Way, a process of interaction that is based on consultations and consensus (Narine, 1998). ASEAN mostly resolves disputes through bilateral, non-formal talks instead of a holistic, diplomatic forum involving all member states. Its high cultural diversity, leading to social fragmentation, is a major factor behind this difficulty in coming up with a common consensus.

Due to this “non-formal” nature of the relations between ASEAN’s member states, a “comfort level” norm has developed in which states’ comfortability is the utmost priority in any decision-making process. The so-called principle of non-interference, and the inviolable nature of state sovereignty, are used as arguments to justify ASEAN’s passiveness in handling its own regional conflicts. What happens, then, if a nation is not comfortable in tackling its disputes and thus brings up non-interference as an argument – a phenomenon that has happened way too often? 

This reflects a weakness in ASEAN’s consensus-based decision-making process. The softness of its institutions too is a source of delay for regional peacebuilding. Though mechanisms for internal dispute settlements are in place, most have not been tried or tested, and the Political-Security Community of ASEAN remains weak (Qin, 2019). It seems that any nation can disregard ASEAN’s decisions too, just like how the Myanmar military junta has not adhered to the five-point consensus (Reuters, 2025c), because of the organization’s non-binding nature. In addition, ASEAN’s institutional weakness makes it prone to foreign involvement. In fact, in certain cases, foreign involvement, especially from the major powers, may ironically prove more effective instead, such as when Trump stepped in during the Thai-Cambodian dispute and successfully called for a truce (Hardianto, 2025). In this way, many have dubbed ASEAN as merely a “talking shop”.

In light of these issues that have the potential to fracture ASEAN, relational multilateralism—though useful in its own respects—must not be the only anchoring praxis. ASEAN can learn from the European Union (EU), for example, as a rules-based multilateral platform to settle disputes among its members. The ASEAN High Council as the authority that has the right to settle disputes among members can be strengthened to ensure fair, long-lasting agreements. Harsher sanctions and tighter norms can be developed to prevent member states from resorting to violence, much like Trump’s threats of halted tariff negotiations to Cambodia and Thailand. 

However, this does not mean that ASEAN must imitate the EU and abandon relational priorities, but to learn from others to compensate for weaknesses while keeping its strong suits pursuant to the local context. After all, diplomacy as well as good relations can serve as a potent instrument at maintaining regional stability, as shown by Southeast Asia transforming into one of the most stable regions in the world; be useful in dispute management, such as in the Ambalat case; and must be strengthened (Qin, 2019; Uli, 2025). In addition to this, ASEAN must resolve any conflict or dispute holistically at the root of the problem, not merely by sweeping it under the rug and hope that it fizzles out.

Conclusion
The recent Thai-Cambodian conflict showcases ASEAN’s weakness in peacebuilding. It often lacks initiative to stop violence and redress the root of the problem. This can be attributed to ASEAN’s focus on being a relational multilateral institution, placing management of good relations as a top priority even at the cost of rules and institution-building. While this is the best for ASEAN’s local context, it has also caused many problems, including delays in conflict management and inability to enforce a decision. Therefore, ASEAN must take steps to compensate for its weakness while keeping its strength, including learning from rules-based multilateral institutions, such as the EU; strengthening relational-based instruments, such as diplomacy; and resolving conflicts at the root of the issue.

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