What Is The Thailand-Cambodia Border Dispute

Running approximately 508 miles between Laos in the North and the Gulf of Thailand in the South, lies the much-disputed Thai-Cambodian border. The dispute is not over the whole border. The controversy is centered around several poorly demarcated areas in the frontier between the two countries and the location of a series of Khmer temple complexes in the Dangrek Mountains. Following major fighting in 2025, a ceasefire remains in place as of August 2026, but both Thailand and Cambodia interpret historical maps and treaties differently.

A Border Shaped by the Dangrek Mountains

The Dangrek Mountains are a low-elevation mountain range, covered with forests and plateau-like high ground. On the Cambodian side of the border, the mountains rise sharply above the country's central lowlands. On the Thai side they grade toward the Khorat Plateau. The disputed border in the Dangrek Mountains was established by the Franco-Siamese Treaty of 1904, signed when Thailand was the Kingdom of Siam and Cambodia was under French colonial rule. The treaty established the border at the watershed line. Later French maps did not always follow the watershed line precisely, leading to large territorial gray areas between the two countries.

Why Preah Vihear Became The Most Famous Dispute

Located on a promontory in the Dangrek Mountains, the ancient temple Preah Vihear, called Prasat Preah Vihear in Cambodia and Prasat Phra Wihan in Thailand, has been at the heart of the dispute for many years. Preah Vihear was initially built as a Khmer Hindu temple, but over time it became a Buddhist site. Although the temple is on the Cambodian side of the escarpment, it is easier to access through Thailand. Cambodia brought the territorial dispute before the International Court of Justice, which ruled on July 15, 1962, that Preah Vihear belonged to Cambodia. The ICJ ordered Thailand to withdraw military forces that had been stationed at the temple since 1954, shortly after the French withdrawal from Southeast Asia.

Tensions between Thailand and Cambodia over Preah Vihear re-escalated in 2008, when Cambodia registered the temple as a UNESCO World Heritage site. Thailand protested the listing, and border clashes between 2008 and 2011 left at least 20 people dead and displaced thousands. Cambodia then requested clarification from the ICJ on which territories exactly were covered under the 1962 ruling. The court first called for both sides to withdraw troops from the area, which was done in 2012.

On November 11, 2013, the International Court of Justice ruled that Cambodia possessed sovereignty over the entire Preah Vihear promontory, not just the temple complex itself. Thailand was ordered to remove military, police, and other personnel from the territory. The ICJ's ruling did not settle disagreements over other disputed portions of the Thai-Cambodian border in the Dangrek Mountains.

Ta Moan Thom and Other Unresolved Temple Areas

Preah Vihear is just one of many Khmer temple sites embroiled in the long border dispute. Known to Thais as Prasat Ta Muen Thom, or Prasat Ta Moan Thom to Cambodians, the temple is a Khmer-Hindu temple dating back to the 11th century, and its territorial status is also in doubt. Originally an important stop on the route between the capital of Angkor and a large administrative center in Phimai in the Khmer Empire, Ta Moan Thom is translated as the "Castle of Grandfather Chicken."

Ta Moan Thom and several other related temples in the area were looted by the Khmer Rouge communist guerrillas during the 1980s and 90s when they controlled the area. The Khmer Rouge dynamited carvings and statues from the complex, selling them on the black market to finance their guerrilla activities. The temple became one of the focal points for the 2025 confrontation between the two countries.

Prasat Ta Krabei, or Prasat Ta Khwai in Khmer and Thai respectively, is a crucial temple complex in the long territorial dispute. Prasat Ta Krabei was also constructed by the Khmer Empire in the 11th century. The name translates to "Grandfather Buffalo Temple," and it is a Hindu holy site dedicated to the god Shiva. Before the 2025 escalation of the territorial dispute, the site was a popular tourist destination in both Cambodia and Thailand. Both countries maintain territorial claims to Ta Krabei and to Ta Moan Thom, and the 1962 ICJ ruling on the territorial disposition of Preah Vihear has no bearing on the ownership of either site.

The May 2025 Clash And The Retaliation That Followed

On May 28, 2025, near the Emerald Triangle and Mom Bei area, where the borders of Thailand, Cambodia, and Laos meet, open fighting erupted. One Cambodian soldier was killed. Both countries accuse the other of initiating the clash, and it is not established which party fired first. On June 15, 2025, Cambodia formally appealed to the ICJ, seeking resolution of the disputed areas of Mom Bei, Ta Moan Thom, Ta Krabei, and Ta Moan Tauch.

The May clash set off months of economic and diplomatic retaliation on both sides. Cambodia banned imports of Thai goods, including food and fuel, and Thailand closed border crossings while restricting internet and electricity links supplied to Cambodia. Crossings including Ban Klong Luk in Sa Kaeo province were shut, cutting off routes used daily by traders and migrant workers.

Tensions intensified further after Thai soldiers were injured in landmine incidents in July, with each government accusing the other of laying the mines. On July 23, 2025, a Thai soldier was seriously wounded by a mine. Thailand recalled its ambassador from Cambodia the same day and announced it would expel the Cambodian ambassador from Thailand, reducing relations between the two capitals to their lowest level in years.

On July 24, major fighting broke out at Ta Moan Thom and expanded to several other points along the border, spreading to at least a dozen sites. Thailand stated that Cambodian troops initiated the attacks using drones and heavy weapons. Cambodia stated that Thai troops entered Cambodian territory and that its own forces were acting in self-defense. Thailand deployed F-16 fighter aircraft against targets within Cambodia, while Cambodia employed artillery and rocket systems. Each government identifies the other as the primary aggressor.

The fighting ran four days and left at least 48 people dead with about 300,000 displaced. A ceasefire was announced on July 28, 2025, in Putrajaya, Malaysia, following talks mediated by Malaysia as ASEAN chair and encouraged by the United States and China.

The Two Governments Still Disagree

Thailand did not accept the June 2025 referral, and the reasons each government gives reach back to the colonial-era documents themselves. Cambodia, relying heavily on French-colonial-era maps, argues that the disputed archaeological sites clearly lie within Cambodian territory, and has favored taking several of the disputed sites to the ICJ for adjudication, claiming that an international ruling would provide a peaceful and final resolution of the competing claims over the disputed territories. The government of Thailand distinguishes the 1962 Preah Vihear ruling from other disputed border regions and wishes the dispute to be resolved through existing bilateral boundary mechanisms, rejecting the Cambodian proposal to take the other disputed territory to the ICJ for settlement.

The July ceasefire held until early December 2025, when armed conflict resumed with each side accusing the other of the moves that led to the clashes. The renewed fighting included airstrikes, rockets, artillery, and large-scale displacement of civilian populations, and it spread from forested regions near Laos to the coastal provinces on the Gulf of Thailand. After roughly three weeks of combat that killed at least 47 people and displaced more than a million civilians, the defense ministers of both countries signed a second ceasefire on December 27, 2025, at a border checkpoint in Thailand's Chanthaburi province. The joint statement committed both sides to maintain current troop deployments without further movement, while border survey and demarcation work resumed through a joint boundary commission.

Where The Dispute Stands Now

As of September 2026, the December 27, 2025 ceasefire agreement remains the governing framework of the contested border regions. The Cambodian government continues to accuse Thai forces of illegally occupying areas it considers to be Cambodian territory. Thailand rejects these claims, stating that the forces in question remain in positions permitted by the ceasefire. On August 26, 2026, Thailand's foreign ministry issued a statement claiming that the Thai government was committed to the terms of the ceasefire and to resolving the territorial dispute through bilateral agreement.

Although the ceasefire remains in place as of August 2026, the disputed areas around the Thai-Cambodian border remain unresolved. Despite International Court of Justice rulings on the Preah Vihear temple complex in 1962 and 2013, several other ancient temple sites remain in question, with Ta Moan Thom and Ta Krabei the most contested. This territorial dispute has gone on for over 100 years, since the treaty between Thailand, then the Kingdom of Siam, and the French colonial government of Cambodia. Colonial-era maps, watershed geography, and the poorly demarcated border through the Dangrek Mountains have contributed to the long-running dispute, and the joint boundary commission established under the ceasefire has yet to produce an agreed line.