July 29, 2025, 2:50 PM View Comments ()

Over the weekend, the leaders of Thailand and Cambodia agreed to an unconditional cease-fire that took effect on July 28. The deal will hopefully end five days of border conflict that has killed dozens of civilians and soldiers on both sides and displaced 300,000 people in the border region.

The deal was brokered by Malaysia, the current holder of the rotating chair of the Association of Southeast Asian Nations (ASEAN), of which the two warring states are members. Both the United States and China had pressed the two sides to end the fighting.

What precipitated the border clashes?

For more than a century, Cambodians and Thais have contested sovereignty over the 11th-century Preah Vihear Hindu temple, currently controlled by Cambodia, as well as several other religious sites along their contested border. The argument stems from France’s demarcation of borders during the colonial era, when Cambodia was part of French Indochina and Thailand remained an independent kingdom. Even though the International Court of Justice in 1962 ruled in favor of Cambodia, Thailand disputes the outcome, and the countries sporadically take up arms to voice their frustrations.

This time, however, personal issues enflamed an already delicate situation. On June 15, Cambodian strongman Hun Sen spoke with Thailand’s now-suspended prime minister, Paetongtarn Shinawatra, in a conversation that Hun Sen, for unknown reasons, decided to record and subsequently leak. In the call, Shinawatra, whose family had been very close to the Huns since the rule of her father and former Thai prime minister, Thaksin Shinawatra, called Hun Sen “uncle” and criticized one of her own Thai military commanders.

The recording, which many Thais interpreted as their prime minister engaging in treason, precipitated a political crisis in Thailand that continues to play out. On July 1, the Thai Constitutional Court suspended her, with the deputy prime minister, Phumtham Wechayachai, ultimately taking over as acting prime minister.

Meanwhile, there are differing theories as to why Hun Sen decided to leak the phone call. One is that he tried to whip up nationalism in political support of his son and current prime minister, Hun Manet. Another is that Hun Sen was offended by Bangkok’s decision to crack down on so-called scamming compounds across the border in Cambodia that have engaged in mass online scams and criminal activities that the Cambodian regime, and Hun Sen personally, have probably profited from. Thai authorities have raided properties on the Thai side of the border and made arrests of suspects believed to be connected to the scams, and Bangkok has shut down telecom towers facilitating it.

What has happened since the conflict reignited?

The latest bout of violence began on May 28 with the death of a Cambodian soldier during a brief exchange of gunfire between Thai and Cambodian troops in the Emerald Triangle region, where the borders of Cambodia, Laos, and Thailand converge. Both sides blamed each other for starting the skirmish; Thailand subsequently closed the border.

A broader conflict, which started on July 24 after a land mine explosion wounded five Thai soldiers the previous day, has resulted in at least 38 deaths of mostly civilians and the forced evacuation of perhaps 300,000 civilians on either side of the border. Observers consider this the most serious and lethal round since a similar border clash in 2011.

Both sides engaged in artillery duels, whether preemptively or in self-defense. They both used drones—Cambodia for surveillance and Thailand for lethal targeting—which marks a new milestone in their conflict and aligns with the global technological shift toward drone warfare. Bangkok’s armed forces dwarf Phnom Penh’s, and the former leveraged its asymmetric advantage in recent days by flying F-16s over Cambodian territory to strike key targets and by deploying the Royal Thai Navy along Thailand’s southern coast. Each side blamed the other for widening the war. Notably, neither side occupied the other’s territory.

How are China and the United States involved?

Thailand is an official U.S. treaty ally but also has strong relations with China. Cambodia is backed by China and hosts a Chinese naval base, one of only two such bases that Beijing has been able to set up worldwide. But there are no indications of either superpower treating the conflict as a proxy struggle to achieve strategic advantage in Indochina. On the contrary, both China and the United States have supported an immediate and unconditional cease-fire deal since the start of the crisis. Both of their representatives attended weekend talks in Malaysia.

Although Chinese President Xi Jinping has not publicly weighed in, Foreign Minister Wang Yi called the situation “distressing and worrying.” Wang further noted that “China is willing to uphold an objective and fair position and play a constructive role for the harmonious coexistence between Thailand and Cambodia.” Wang, however, did not miss the opportunity to score some diplomatic points, quipping that the crisis was part of the “enduring damage caused by Western colonizers.”

U.S. President Donald Trump urged both nations to come to a cease-fire agreement on July 26, later threatening: “We happen to be, by coincidence, currently dealing on Trade with both Countries, but do not want to make any Deal, with either Country, if they are fighting—And I have told them so!” Once Malaysia brokered the deal, Trump predictably, undeservingly, and bombastically tried to take credit, claiming, “I have now ended many Wars in just six months—I am proud to be the President of PEACE!” Using more traditional diplomatic language, U.S. Secretary of State Marco Rubio made clear that he and the administration “expect the governments of Cambodia and Thailand to fully honor their commitments to end this conflict.”

Will the cease-fire hold?

Like most cease-fires, this one also faces potential pitfalls and uncertainties that could derail it. Cambodia and Thailand are facing a combustible mix of historical grievance, border disputes, domestic political crises, and militarized nationalism that augur against maintaining the cease-fire deal.

However, both sides also have strong incentives to abide by the pact, not least to avoid further death and destruction in their territories that could lead to political unrest, economic sanctions, or even the hijacking of the conflict by China and the United States for the purposes of great-power competition. Since the end of the colonial era, there is no history of Thai-Cambodian border conflicts ever leading to a wider war.

All considered, the cease-fire stands a fair to good chance of success over the coming days, weeks, and months. Thailand’s domestic political crisis and other factors particular to this round of fighting will eventually pass. To be sure, deep historical grievance over Preah Vihear and other contested temples will likely remain, suggesting that future rounds of conflict could erupt anytime.

What else can be done to preserve the peace?

Ultimately, Cambodia and Thailand must reach an agreement on the sovereignty status of Preah Vihear and on access to the site for each other’s citizens. Barring that, the two sides need to maintain regular consultations on the dispute to ensure that there are no miscommunications or misperceptions that could inadvertently lead to another border crisis or even spiral into a full-fledged war.

Malaysia’s ability to broker a cease-fire deal—with the weight of ASEAN behind it—is a good sign. It suggests that Thailand’s status as one of the strongest military powers in Southeast Asia doesn’t keep it from negotiating fairly with a weaker member of the bloc. At the outset of the conflict, Bangkok resisted international mediation, preferring instead to engage in bilateral talks in order to maximize its strategic advantages. As the smaller and weaker state, Cambodia preferred an internationalized approach. However, Bangkok’s decision to yield to Malaysia as ASEAN chair shows that Thailand—at least with its current government—still has respect for the bloc and wants to be seen as a peaceful and productive member.

Finally, much will depend on whether Washington and Beijing continue to urge restraint and refrain from interpreting Preah Vihear as the geopolitical domino that could determine which great power controls Indochina. If that interpretation takes hold and the conflict worsens, then the United States and China could deepen their support for their respective friends.

The best way Washington can avoid this is to intimate to Bangkok that although they are security allies, the United States will not defend Thailand if it escalates militarily. Likewise, Beijing could convey to Phnom Penh that China would remain noncommittal if conflict breaks out again.