Cambodia–Thailand border
The natural border between Cambodia (left) and Thailand (right) in Ban Nong Khanna Samakkhi area, Village No.8, Ta Miang Subdistrict, Phanom Dong Rak District, Surin Province, Thailand
Characteristics
Length	817 kilometres
History
Current shape	1907

TheCambodia–Thailand border is the international border betweenCambodia andThailand. The border is 817 km (508 mi) in length and runs from the tripoint withLaos in the north-east to theGulf of Thailand in the south.^[1]

The border starts in the north-east at the tripoint with Laos at Preah Chambot peak in theDângrêk Mountains and follows the crest of the mountains westwards.^[2] Upon leaving the mountains the border turns south-westwards in a broad arc, occasionally utilizing rivers such as theSvay Chek, theSisophon, the Phrom Hot andMongkol Borei. It then proceeds south, partly along theCardamom Mountains, terminating at the Gulf of Thailand coast. This latter section runs very close to the Gulf, producing a long, thinstrip of Thai territory.^[2]

The boundary area has historically switched back and forth between various Khmer and Thai empires.^[2] From the 1860sFrance began establishing a presence in the region, initially in modernCambodia andVietnam, and later Laos, with the colony ofFrench Indochina being created in 1887.^[2][3] In 1867 a Franco-Thai treaty confirmed Thai ownership of theBattambang andAngkor (Nakhou Siemrap) regions.^[2][3] In 1896, Britain (based inBurma) and France agreed to leave Siam (the then name for Thailand) as abuffer state between their respective colonies.^[2] However France continued to expand at the expense of Siam, annexing northern Cambodia in 1904 and thenBattambang,Sisophon andSiem Reap in 1907, whilst cedingTrat to Siam. The modern Cambodian-Thai border was as such delimited through several treaties between France and Siam between 1867and 1907.^[2][3] Following theJapanese invasion of French Indochina in 1940 areas ceded to France in 1904 and 1907 were returned to Thailand, however this was reversed following Japan's defeat and the pre-war border restored in 1946.^[2][3]

Cambodia gained independence in 1953, and since then the two states have had a fractious relationship.^[4] ACambodian–Thai border dispute arose in the late 1950s over the ownership ofPreah Vihear, a temple in the Dângrêk Mountains, adjacent to the border.^[2] In 1962 the case was referred to theInternational Court of Justice, which ruled in favour of Cambodia, however Thailand expressed reservations as to the outcome.^[2][5] The mid-1960s also saw a dispute over ownership ofKo Kut island.^[3] These disputes faded as Cambodia became engulfed in a series of conflicts in the following decades and the disastrous rule of theKhmer Rouge, with thousands of refugees crossing the border.^[3] By 1981, over 250,000 Cambodian and Vietnamese refugees lived in twenty camps along the border, supported by international aid agencies and theUnited Nations Border Relief Operation.^[6]

Sporadicfighting broke out along the border following Vietnam'sinvasion of Cambodia in 1979 which forced the Khmer Rouge to flee to camps on the border with Thailand, using them as a base throughout the 1980s until Vietnam withdrew from the country in 1989. On 18 February 1994, the Khmer Rouge led byPol Pot (Saloth Sâr) rebuilt their headquarters atDângrêk Mountains located inAnlong Veng near the Thai border.^[7] In an effort to stop Khmer Rouge infiltration from Thailand, Cambodia built a largefortified fence along the border in the second half of the 1980s.^[8][9]

Since the advent of peace in Cambodia in the early 1990s relations with Thailand have once again soured over the Preah Vihear issue, as well as, to a lesser extent, Ko Kut island.^[3] A border commission was set up in 1995 in an attempt to settle the issues peacefully, however by 2013 it had made little progress and a full border demarcation satisfactory to both sides remained outstanding.^[3][10][11]

Armed fighting broke out at various timesfrom 2008 to 2011. As of September 2022, government officials said border demarcation had been completed in 13 areas, and that the remaining 11 were under negotiation.^[12]

On 28 May 2025, oneRoyal Cambodian Army soldier was killed after a Thai patrol encountered Cambodian soldiers digging trenches. Both Cambodia and Thailand accused the other of trespassing on their respective territories and firing first.Phumtham Wechayachai, Thailand's Defense Minister, claimed that opening fire was not intended on both sides.^{[13][14][15][16]} Cambodia stated that it will litigate the dispute with theInternational Court of Justice.^[17]

In July 2025,the conflict was reignited with both sides' military attacking each other. Thailand also sealed all land border crossings with Cambodia. Multiple civilians are reported to be killed.^[18] On 24 July 2025, Cambodian Prime MinisterHun Manet submitted a request to the United Nations Security Council to call for an urgent meeting to stop Thai's aggression.^[19] UNSC held the meeting on 25 July 2025.^[20] With mediation effort from 2025 ASEAN Chair country Malaysia, as well as call for cease fire from U.S. PresidentDonald Trump to both countries, Hun Manet and Thailand Acting Prime MinisterPhumtham Wechayachai met in Kuala Lumpur for a peace talk on 28 July 2025. Both countries have agreed on an immediate and unconditional ceasefire taking effect on 12:00 on 29 July 2025.^[21]

As of 2019^[update], there were seven permanent border crossings, one temporary border crossing, nine checkpoints for border trade and one checkpoint for tourism which is currently closed.^[22]

One temporary border crossing exists for the construction of theThai-Cambodia Friendship Bridge [th] only, which will become a permanent border crossing in the future.

There are 9 checkpoints officially recognized by the Ministry of Interior which are open for cross-border local trade only, located inUbon Ratchathani,Buriram,Sa Kaeo,Chanthaburi andTrat provinces. Entering the opposite country beyond these checkpoints and their associated markets is illegal.

There is one checkpoint for tourism, which is currently closed since June 2008 due to thePreah Vihear dispute and eventual cession ofPreah Vihear to Cambodia.

• Cambodia–Thailand relations
• 2008–2013 Cambodian–Thai border crisis
• 2025 Cambodia–Thailand border conflict
• Cambodian humanitarian crisis
• Vietnamese border raids in Thailand
• Indochina refugee crisis
• Nong Chan Refugee Camp
• Nong Samet Refugee Camp
• Sa Kaeo Refugee Camp
• Site Two Refugee Camp
• Khao-I-Dang

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