War Comes to the ASEAN Family

BANGKOK | 31 JULY 2025

In friendlier times, Cambodia’s Hun Sen had agreed to host the fourth meeting of ASEAN’s informal advisory group for Myanmar, headed by Thailand’s Thaksin Shinawatra.

This was announced by Malaysian Prime Minister Anwar Ibrahim, whose country is this year’s ASEAN chair, at the ASEAN leaders’ summit in May. But, how now?

The very public breakdown of the decades-long friendship between Hun Sen and Thaksin Shinawatra, the heads of two political families and fathers of the sitting prime ministers (though PM Paetongtarn has been suspended), has all but torpedoed Malaysia’s initiative to bring in some senior figures in ASEAN to help with the four-year-old crisis in Myanmar.

Whatever one thinks of this initiative, this side story to toxic Thai-Cambodia ties underscores how the two countries’ armed confrontation in July eats away at the core of the community ASEAN says it has become – at a time when it is navigating a fracturing global landscape as well as a trade war.

The Thai-Cambodian clashes have brought war into ASEAN’s neighbourhood ahead of the organisation’s 60th anniversary in 2027. 

The regional grouping is much more used to seeing members undergo internal troubles, like that of Myanmar, but an armed confrontation between two member states strikes at the heart of ASEAN’s reason for being.

It counts as its biggest achievement its prevention of war and conflict among its member states. Its diplomats like to recall how ASEAN was able to make a family – despite disputes among its members – out of a set of nations whose officials would not even sit at the same table in decades past, divided as they were along Cold War lines. ASEAN’s 1976 Treaty of Amity and Cooperation and 2007 Charter, which are legally binding instruments, include the principle of “renunciation” of the threat or use of force of aggression.

Against this backdrop, the Thai-Cambodia border violence is a deep, bleeding wound for ASEAN. 

“Its gravity cannot therefore be exaggerated,” wrote former Indonesian foreign minister Marty Natalegawa and former Malaysia foreign minister Syed Hamid Albar, referring to the clashes in a 28 July statement entitled ‘The Guns Must Be Silenced’.

The eruption of military clashes in July, which escalated from a skirmish on 28 May, has also all but wrecked the strategic partnership that Thailand and Cambodia agreed to “elevate” their ties to just in February 2024. This step, which had hefty diplomatic and political weight, was formalized during Cambodian Prime Minister Hun Manet’s state visit to Thailand. (Cambodia’s official announcement is here, and Thailand’s here.) The year 2025 also marks the 75th year of Thai-Cambodian diplomatic ties.

As neighbours, Thailand and Cambodia are quite deeply connected. Cambodian figures put at over 1.2 million the number of its migrant workers in Thailand, making them a key contributor to the country’s economy. The second largest group of migrants after Myanmar, Cambodians ­– huge numbers of them ­– are heading home or waiting to cross through border points. Cambodians also come to Thailand for medical treatment.

Thailand is a major investor in Cambodia, and is Cambodia’s fourth largest trade partner. Bilateral trade reached 10 billion dollars in 2024, a huge amount of which passes through now-shut borders. Before this conflict, the two countries aimed to hit a trade volume of 15 billion this year. Thais make up the bulk of tourists in Cambodia and the two countries are often linked destinations for other travellers, but tourism has fallen to near zero.

For Thailand too, this confrontation at its eastern border with Cambodia adds to another border it is already having to watch closely – on the west with Myanmar.

SOCIAL MEDIA BATTLEFIELDS

The Malaysia-brokered ceasefire that began on 28 July midnight is holding despite accusations by both sides about violations, but online battles between Cambodians and Thailand rage on.

Border residents lament how much worse the damage is this time around, compared to those in 2008 to 2011, because today’s weaponry is much more advanced. (Thailand used American F-16s as well as Swedish Gripen jets, Cambodia used Soviet-origin BM 21 rocket launchers.)

But there is also another lethal weapon these days: social media. Insults and competing claims are being lobbed like missiles in online battlefields, made much more incendiary by a mix of disinformation and long-held prejudices and stereotypes that have deep roots in history as well more ‘modern’ differences ­– varying political cultures, and current volatility in Thailand’s revolving-door politics.

Facebook has become an arena where arguments have broken out between colleagues and left some cross-border friendships in tatters.

All this is happening in a wider world disorder, where war is no longer a don’t-go-there option and where the number of armed conflicts has been increasing. Not too long ago, we saw India and Pakistan have a go at it too, elsewhere in Asia, apart from Russia’s invasion of Ukraine, Israel and the US’ attack on Iran, Myanmar’s continued conflict.

Taking place in a backdrop of different political cultures in Thailand and Cambodia, this contagion has now reached ASEAN’s neighbourhood.

In the din of the information war around the Thai-Cambodian confrontation, I found myself looking deeper into a few points:

1 | Is it ASEAN or Malaysia that has taken the lead in brokering the ceasefire?

There have been pats on the back for Malaysia as well as for ASEAN for taking action. But so far, it seems to be more about Malaysia as ASEAN chair and Anwar himself deciding to invest diplomatic and political capital in addressing the Thai-Cambodia tensions.

These are early days, but ASEAN looks set to be roped in at some level as it has endorsed a Malaysian proposal that an observer team be set up from among ASEAN member states, and that it would act as coordinator.

Historically, mediation efforts have depended on the interest and initiative of individual ASEAN chairs. For instance, Indonesia, which was ASEAN chair during Thai-Cambodian border clashes in 2011, took on a mediator role and its foreign minister at the time Marty Natalegawa, did shuttle diplomacy.

The Nikkei Asia Review reports that the 28 July meeting in Malaysia used the ASEAN secretariat’s “templates from communiques and news releases for earlier tangles along the Thai-Cambodian border, including in 2011 and 2020”.

Malaysia’s defence chief has been discussing with Thai and Cambodian counterparts the mechanisms to implement and monitor compliance with the ceasefire on the ground, as a way of trying to build confidence. Armed forces chief Gen Tan Sri Haji Mohammad Nizam bin Haji Jaffar visited Cambodia and Thailand on 29-30 July for this purpose and there has been talk of involving defence attaches from ASEAN.

There are a few more useful things to note. The official statement announcing the “immediate and unconditional” ceasefire at the “special meeting hosted by Malaysia” on 28 July between Cambodia and Thailand’s leaders was published on the Malaysian foreign ministry website, with the logo of Malaysia’s chairmanship of ASEAN for 2025. This statement did not appear on the ASEAN website.

There have been two ASEAN’s official statements thus far, by its foreign ministers.

Their three-paragraph statement, dated 27 July and published the next day, welcomed Malaysia’s hosting of the meeting to discuss a ceasefire between Thailand and Cambodia. On 31 July, they issued a four-paragraph statement saying “we hope that the ceasefire agreed by both sides will be fully implemented in good faith”.

How high-level and how deep ASEAN involvement will be is something to watch. There have been calls for a leaders’ meeting from different quarters. The second ASEAN leaders’ summit this year is due in October.

2 | What were the US’ and China’s roles in the ceasefire talks in Malaysia?

Does this signal big powers’ significant involvement, or was it more about optics? Does it indicate more active involvement in what has been described as talks “co-organised” by the US, or a diplomatic recognition of the nudge from US President Donald Trump’s conversations with the Thai and Cambodian leaders? (Some would ask – is this part of Trump’s quest for a Nobel Peace Prize.) Was China’s presence meant to then strike some balance since the US was going to be there?

China’s participation appears to have first come up in a Facebook post by Cambodian Prime Minister Hun Manet at 11 pm of 27 July, the night before the ceasefire talks.

Words matter hugely in diplomacy, so it’s worth looking at the phrasing in the joint statement announcing the “immediate and unconditional” ceasefire at the “special meeting hosted by Malaysia” between Cambodia and Thailand’s leaders. The first paragraph describes the meeting as “co-organised by the United States of America with the active participation of the People’s Republic of China”.

A look at the photo of the talks shows the Chinese and American ambassadors to Malaysia sitting at both ends of the room – with the US side behind the table where Cambodia’s Hun Manet is seated and the Chinese side behind Thai deputy PM Pumtham Wechayachai’s table.

Some see US and Chinese presence as a positive factor, but it does trigger discomfort given ASEAN’s carefully nurtured preference for not choosing sides. The ASEAN-style instinct would be to lean towards a process that is rooted within its family, not dependent on or shaped by external forces.

3 | In June, Cambodia said it brought the matter of its border disputes with Thailand around four temples to the International Court of Justice. Exactly what kind of action was this?

Cambodian PM Hun Manet’s post on Facebook on 15 June 2025 said that Cambodia was sending an “official letter” to the ICJ. It does seem like it was formal communication, and not a full case as it is not listed in pending cases or cases under deliberation on the ICJ website. There is no ICJ press release on the matter, and searches for ‘Cambodia’ point to the 15 June 1962 decision on the Preah Vihear temple being on Cambodian territory and the Court’s interpretation of this decision handed down in November 2013.

Hun Manet also pointed out that he was sending the letter on the 63rd anniversary of the ICJ ruling that the Preah Vihear was Cambodia’s.

ASEAN WAITED “TOO LONG” BEFORE TAKING ACTION IN THE PAST

In its 2011 report (a must-read) after the clashes of that time around Preah Vihear, the International Crisis Group noted that there had been a “history of broken verbal ceasefires” between the two countries. It said there was no real and lasting end to hostilities without a written ceasefire and sustained ASEAN involvement in pushing the withdrawal of troops from the disputed area, as the ICJ also ordered.

After those earlier clashes, the ASEAN chairmanship moved on across different member states and the organisation, as well as the Thai and Cambodian governments, played the matter down in the interest of better ties. Border demarcation efforts were not finished, things were left unresolved and the two countries’ political leaders pursued other areas of cooperation. But that trust deficit continued – and fast forward to the five days of armed confrontation in July.

“With hindsight, it is clear ASEAN waited too long to intervene,” said the report, entitled ‘Waging Peace: ASEAN and the Thai-Cambodian Border Conflict’ – and this was about the 2011 clashes, 14 years ago. (There were 24 clashes recorded at the shared border near Preah Vihear in 2011 and “more than 30 incidents of violence” in the July 2025 clashes, ACLED says in its new update. It also says that the last direct clash between the Thai and Cambodian armies was in 2014.)

ASEAN needs to do more in conflict prevention and resolution, going to lengths that include deploying and keeping observers at the border and steering the situation through negotiations and not just a pause in armed conflict, the report said.

Recounting ASEAN’s handling of the Thai-Cambodia friction through the years, the report explained: “The Singapore chair had a difficult call to make in 2008, as there had not yet been any violence. The bilateral option still had credibility in a way it no longer does. Of course, Thailand, as the chair from mid-2008 through 2009, could not act in a dispute to which it was party. Vietnam in 2010, however, should have shown more concern. ASEAN, if it is to do better in future cases, needs to focus more on the substance of being a community, not just the form.”

“The threshold to intervene in such conflicts needs to be much lower. The deployment of troops by a member state to the border of another member state should be an obvious trigger for a political intervention,” it argued.

OVERDEPENDENCE ON THE ASEAN CHAIR

“The Thai-Cambodian border conflict underlines that ASEAN should be prepared to take more pre-emptive and urgent action to prevent open hostilities between member states. Its foreign ministers in special session need to put more political force behind their collective decisions,” the ICG report said. “It cannot count on always being fortunate enough to have a chair willing to give peacemaking a chance, as Indonesia has been in 2011. It needs to devise ways to intervene not dependent on annual rotation.”

In 2025, Malaysia is taking on the role that Indonesia attempted more than a decade ago, with five months left in its chairmanship of ASEAN. It is the Philippines’ turn next year, since ASEAN has decided against letting Myanmar take its turn as chair.

A Thai employee, thinking about what can happen now to Thailand and Cambodia, asked: “Are we going to end up (hateful of each other) like Russia and Ukraine?

(END/Reporting ASEAN)