General information
Type of Incompatibility: Territory
Comment on Type of Incompatibility: The border conflict between Thailand and Cambodia was to a large extent caused by the use of different maps. Cambodia used a map from 1909, created by a Franco-Cambodian commission following agreements between France and Thailand in 1904 and 1907. Thailand on the other hand used an American military map from 1954. Throughout the conflict, the frontier shifted and clashes occurred along the whole border. One reason for this was reportedly that several of the border markings were kilometers apart which caused uncertainty regarding where the actual border line was. The most frequently disputed area was however the ancient Temple of Preah Vihear, located at the northern Thai-Cambodian border.
Territory: Common Border
Date of first stated goal of incompatibility: 1953-12-31
Comment on date of first stated goals of incompatibility: When the Cambodia gained independence from France in 1953, Thai polices forces occupied the ancient Temple of Preah Vihear. Cambodia immediately claimed to have sovereign right over the Temple and negotiations between the two parties were held. The right to the territory had been disputed by Cambodia and Thailand even before 1953 but this was the first time Thailand had occupied the Temple since the World War II and the first time Cambodia claimed the territory as a sovereign country.
Date of first use of armed force: 1965-06-01
Comment on first use of armed force: There is limited reliable information on the developments after the International Court of Justice’s decision to support Cambodia’s claim of having sovereign right of the Temple and its surrounding territory. The first recorded armed violence related to border disputes between Thailand and Cambodia was in June 1965 when Thai and Cambodian forces allegedly clashed in heavy fighting. It is possible that armed violence was used earlier than this date.
Date of first battle related death: 1975-12-14
Comment on first battle related death: A number of clashes between Thai and Cambodian forces (Khmer Rouge) took place during 1975. Several fatalities were reported in clashes between Thai border police and Cambodian forces on 12-15 December. There is limited reliable information regarding the disputed border and its related clashes between Thai and Cambodian forces. It is therefore possible that the first battle related death occurred earlier than this date. The clashes in mid December was however the first recorded incident of battle related death in this conflict.
Date of conflict reached 25 battle releated deaths: 1977-12-31
Comment on conflict reached 25 battle releated deaths: The fighting between Thai forces and Cambodian forces along the border escalated in 1977. Clashes were reported at a number of locations along the border, but the most notable ones took place in the Prachinburi province, located east of Bangkok. There is limited reliable information regarding the disputed border and its related clashes between Thai and Cambodian forces. It is therefore possible that the conflict reached 25 battle related deaths before this date.
Annual information
This section contains annual information systematically collected by the UCDP.
1975
Primary Parties: -
Dimension: Interstate
| Estimated Fatalities | |
|---|---|
| High | 1 |
| Best | 1 |
| Low | 0 |
Numbers include fatalities for all dyads both active and inactive for this year
1977
Primary Parties: Government of Cambodia (Kampuchea) - Government of Thailand
Dimension: Interstate
Comment on Dimension: The conflict between Thailand and Kampuchea was mainly caused by the use of different border maps and the lack of border markings along the border. Along parts of the border, the markings were several kilometres apart. Throughout the conflict, the frontier shifted and clashes occurred along the whole border. The most frequently disputed area was however the Temple of Preah Vihear, located at the northern Thai-Kampuchean border.
| Estimated Fatalities | |
|---|---|
| High | 25 |
| Best | 25 |
| Low | 0 |
Numbers include fatalities for all dyads both active and inactive for this year
1978
Primary Parties: Government of Cambodia (Kampuchea) - Government of Thailand
Dimension: Interstate
Comment on Dimension: The conflict between Thailand and Kampuchea was mainly caused by the use of different border maps and the lack of border markings along the border. Along parts of the border, the markings were several kilometres apart. Throughout the conflict, the frontier shifted and clashes occurred along the whole border. The most frequent disputed area was however the Temple of Preah Vihear, located at the northern Thai-Kampuchean border.
| Estimated Fatalities | |
|---|---|
| High | 25 |
| Best | 25 |
| Low | 0 |
Numbers include fatalities for all dyads both active and inactive for this year
1995
Primary Parties: -
Dimension: Interstate
| Estimated Fatalities | |
|---|---|
| High | 31 |
| Best | 7 |
| Low | 7 |
Numbers include fatalities for all dyads both active and inactive for this year
1997
Primary Parties: -
Dimension: Interstate
| Estimated Fatalities | |
|---|---|
| High | 4 |
| Best | 0 |
| Low | 0 |
Numbers include fatalities for all dyads both active and inactive for this year
1998
Primary Parties: -
Dimension: Interstate
| Estimated Fatalities | |
|---|---|
| High | 12 |
| Best | 12 |
| Low | 12 |
Numbers include fatalities for all dyads both active and inactive for this year
1999
Primary Parties: -
Dimension: Interstate
| Estimated Fatalities | |
|---|---|
| High | 0 |
| Best | 0 |
| Low | 0 |
Numbers include fatalities for all dyads both active and inactive for this year
2008
Primary Parties: -
Dimension: Interstate
| Estimated Fatalities | |
|---|---|
| High | 2 |
| Best | 2 |
| Low | 2 |
Numbers include fatalities for all dyads both active and inactive for this year
2009
Primary Parties: -
Dimension: Interstate
| Estimated Fatalities | |
|---|---|
| High | 5 |
| Best | 2 |
| Low | 2 |
Numbers include fatalities for all dyads both active and inactive for this year
2011
Primary Parties: Government of Cambodia (Kampuchea) - Government of Thailand
Dimension: Interstate
| Estimated Fatalities | |
|---|---|
| High | 36 |
| Best | 29 |
| Low | 29 |
Numbers include fatalities for all dyads both active and inactive for this year
2012
Primary Parties: -
Dimension: Interstate
| Estimated Fatalities | |
|---|---|
| High | 0 |
| Best | 0 |
| Low | 0 |
Numbers include fatalities for all dyads both active and inactive for this year
2013
Primary Parties: -
Dimension: Interstate
| Estimated Fatalities | |
|---|---|
| High | 0 |
| Best | 0 |
| Low | 0 |
Numbers include fatalities for all dyads both active and inactive for this year
2014
Primary Parties: -
Dimension: Interstate
| Estimated Fatalities | |
|---|---|
| High | 0 |
| Best | 0 |
| Low | 0 |
Numbers include fatalities for all dyads both active and inactive for this year
2015
Primary Parties: -
Dimension: Interstate
| Estimated Fatalities | |
|---|---|
| High | 0 |
| Best | 0 |
| Low | 0 |
Numbers include fatalities for all dyads both active and inactive for this year
2023
Primary Parties: -
Dimension: Interstate
| Estimated Fatalities | |
|---|---|
| High | 0 |
| Best | 0 |
| Low | 0 |
Numbers include fatalities for all dyads both active and inactive for this year
2025
Primary Parties: Government of Cambodia (Kampuchea) - Government of Thailand
Dimension: Interstate
| Estimated Fatalities | |
|---|---|
| High | 442 |
| Best | 252 |
| Low | 249 |
Numbers include fatalities for all dyads both active and inactive for this year
Peace agreements
Name of peace agreement: Kuala Lumpur Peace Accord
Date when warring parties signed the agreement: 2025-10-26
Conflict Archive
This section contains annual information no longer systematically collected by the UCDP.
1975 Conflict Archive
Terminated: NO
1977 Conflict Archive
Comment on Activity: Following the negotiations between Thailand and Kampuchea (Cambodia was renamed Kampuchea in 1975) in June 1976, the border was reopened for limited trade (it was closed in April 1975) on 30 August 1976. Despite a relative calm in the beginning of the autumn, the fighting was renewed on 22 November in the Thai coastal province of Trat. The tense situation was aggravated even further in late January 1977 when Kampuchean troops crossed the border into the Prachinburi province, located east of Bangkok and raided three villages. Clashes between Kampuchean troops and Thai border police followed the raids. All three villages were located in an area with few border markings and both sides claimed that the villages were within their own territory.
Parts of the border were closed once again and despite some conciliatory gestures from both sides during October and November, border clashes continued throughout 1977.
The Kampuchean authorities claimed that the Thai military was supporting Kampuchean rebels, named “Free Khmers”, while the Thai authorities reported several attacks on Thai villages close to the border.
Comment on Yearly Battle Related Deaths: The number of battle-related deaths in this conflict is unclear, but activity at the least surpassed 25 battle-related deaths.
Negotiations: NO
Third party involvement: NO
Victory: NO
Terminated: NO
1978 Conflict Archive
Comment on Activity: The relations between Thailand and Kampuchea remained tense in 1978, with repeated clashes during mainly the first half of 1978. There were however some conciliatory steps taken. A Thai delegation visited the Kampuchean capital Phnom Penh on 30 January – 2 February. The outcome of the visit consisted of an agreement to implement the joint communiqué drafted on 31 October 1975. The communiqué aimed to normalise relations, resume economic and trade relations and establish diplomatic relations in terms of exchanging ambassadors.
Towards the end of the year, the situation stabilized along the Thai border, reportedly due to increased border tensions along the border between Kampuchea and Vietnam. However, at the end of the year there had been no progress on the actual question of the exact location of the border between Thailand and Kampuchea.
Comment on Yearly Battle Related Deaths: The number of battle-related deaths in this conflict is unclear, but activity at the least surpassed 25 battle-related deaths.
Negotiations: YES
Comment on Negotiation: Negotiations were held by the parties in the Kampuchean capital Phnom Penh on 30 January – 2 February. The outcome of the talks consisted of an agreement to implement the joint communiqué drafted on 31 October 1975. The communiqué aimed to normalise relations, resume economic and trade relations and establish diplomatic relations in terms of exchanging ambassadors.
No real progress on implementing the joint communiqué had been achieved at the end of 1978.
Third party involvement: NO
Victory: NO
Terminated: YES
Type of termination: Other
Date of termination: 1978-12-31
Comment on Termination: During the second half of 1978, the Kampuchean regime faced an increased threat from Vietnam and in December the fighting escalated along the Kampuchean-Vietnamese border. The Kampuchean regime’s focus shifted from the Thai border to the Vietnamese border and the border clashes with Thailand eventually ceased. The question of the exact location of the border between Kampuchea and Thailand was, however, not solved. The fighting along the Kampuchean-Thai border continued during the following years, but was then related to the conflict over governmental power in Cambodia.
1995 Conflict Archive
Terminated: NO
1997 Conflict Archive
Terminated: NO
1998 Conflict Archive
Terminated: NO
1999 Conflict Archive
Terminated: NO
2008 Conflict Archive
Terminated: NO
2009 Conflict Archive
Terminated: NO
2011 Conflict Archive
Comment on Activity: 2011 proved to be the most violent year in more than three decades as the interstate conflict between Cambodia and Thailand once again became active for the first time since 1978. The conflict escalated on 4 February when Thai and Cambodian troops exchanged fire in the vicinity of the Preah Vihear temple. It was unclear who provoked the clash which ended with a truce later the same day. However, the truce proved to be fragile as the movement of Thai tanks was enough to provoke renewed clashes. For three successive days, Thai and Cambodian troops exchanged fire, despite new attempts to end the violence through a ceasefire agreement on 5 February. Both sides suffered fatalities and three civilians were reportedly killed as stray bullets and rockets hit adjacent settlements. In addition, the skirmishes left thousands of civilians displaced. Despite the ostensible step towards an observation mission, Thailand proved to be resistant during the following meeting, thus continuing to stall the talks. The negotiations regarding the mission reached an inevitable deadlock in late April as Thailand demanded Cambodia to withdraw its troop before deploying Indonesian observers. As the attempt to solve the conflict faded with the Thai demand, the Thai-Cambodian relation deteriorated and new fighting erupted on 22 April in the Thai province Surin, thus the conflict had spread beyond the Preah Vihear area. Cambodia had been occupying the Ta Krabei temple in Surin and the new clashes started when Cambodian troops deployed in the area fired at Thai troops. A ceasefire was reached the same day but was quickly broken as fighting continued until 5 May. During the skirmishes, both parties accused each other of violating international law by deliberately targeting civilians. At the ASEAN summit in Jakarta on 3 May, Thailand refused to sign an agreement regarding observers, thus hampering progression once more. During this second round of fighting, both parties suffered casualties. In addition, an estimate of 45 000 people had been displaced.
Negotiations: YES
Comment on Negotiation: In order to settle the prolonged dispute between the two states, the UN Security Council assigned the Association of Southeast Asian Naitions ( ASEAN )to resolve the conflict. A step towards an increased regional involvement was taken after the February clashes when the Security Council decided to hold a three-party talk including Indonesia (ASEAN chairmanship in 2011), Thailand and Cambodia, where both parties expressed their wish for a peaceful solution. The meeting resulted in Cambodia stressing the importance of ASEAN observers at the border while Thailand showed a resilient stance regarding such a request. However, the Thai foreign ministry later changed its mind and decided to discuss the deployment of outside observers.
Despite the ostensible step towards an observation mission, Thailand proved to be resistant during the following meeting, thus continuing to stall the talks. The negotiations regarding the mission reached an inevitable deadlock in late April as Thailand demanded Cambodia to withdraw its troop before deploying Indonesian observers. As the attempt to solve the conflict faded with the Thai demand, the Thai-Cambodian relation deteriorated and new fighting erupted on 22 April in the Thai province Surin, thus the conflict had spread beyond the Preah Vihear area. Cambodia had been occupying the Ta Krabei temple in Surin and the new clashes started when Cambodian troops deployed in the area fired at Thai troops. A ceasefire was reached the same day but was quickly broken as fighting continued until 5 May. During the skirmishes, both parties accused each other of violating international law by deliberately targeting civilians. At the ASEAN summit in Jakarta on 3 May, Thailand refused to sign an agreement regarding observers, thus hampering progression once more. During this second round of fighting, both parties suffered casualties. In addition, an estimate of 45 000 people had been displaced.
Third party involvement: YES
Third party involvement names: Association of Southeast Asian Nation (ASEAN)
Comment on Third Party Involvement: The Association of Southeast Asian Nation (ASEAN) has been assigned (by the UN) the task to take over a significant part of the negotiation between Cambodia and Thailand regarding the dispute over the Preah Vihear temple. The aim of involving ASEAN is to increase the regional responsibility. During 2011, the talks mainly focused on the potential deployment of of independent (Indonesian) observers in the disputed area.
Victory: NO
Terminated: YES
Type of termination: No or Low Activity
Date of termination: 2011-12-31
Comment on Termination: The conflict became terminated by the end of 2011 due to a lack of activity in 2012.
2012 Conflict Archive
Terminated: NO
2013 Conflict Archive
Terminated: NO
2014 Conflict Archive
Terminated: NO
2015 Conflict Archive
Terminated: NO
2023 Conflict Archive
Terminated: NO
2025 Conflict Archive
Comment on Activity: The border conflict between Thailand and Cambodia, which had been inactive for several years, flared up once more during 2025. The first fatality occurred in May, when a Cambodian soldier was killed after an exchange of gunfire at a part of the Cambodian-Thai border that is still undelimited. This resulted in tensions between the states, a worsening of their diplomatic relations, and an increased military presence in the border region. More extensive violence followed in late July, when small arms fire quickly escalated into use of heavier weaponry. It is unclear what caused the outbreak of the clashes, which started on the 24th and lasted until the 28th of July, as both states claim the other triggered the escalation. Aside from military fatalities, 23 civilians were also killed during the July clashes and up to 300,000 people had become displaced in the border region. The fatalities were primarily localized to the border along the Thai provinces Surin, Sisaket, and Ubon Ratchathani. On the Cambodian side, this corresponds to the border along the Oddar Meanchey and Preah Vihear provinces. After four days of fighting, they agreed to end hostilities and implemented a ceasefire after talks were held in Putrajaya, Malaysia. The ceasefire took effect on the 28th of July at midnight and halted clashes.
The commitment to ending hostilities continued, and on October 26th the Cambodian and Thai governments signed the Kuala Lumpur Peace Accord. The parties reiterated their commitment to peace, refrainment from use of force, and their respect for international boundaries. They also agreed to the establishment of an observation team consisting of personnel from ASEAN (Association of Southeast Asian Nations) member states, to ensure the implementation and effectiveness of the ceasefire. The parties also agreed to partake in confidence-building measures, aiming to restore and maintain mutual trust as well as decrease negative public sentiment. Furthermore, they also reaffirmed their commitment to solving the border dispute through peaceful means and international law, and using the established border committees to address such issues. The agreement was signed by both the governments of Thailand and Cambodia, as well as Malaysia and the United States who were present as witnesses.
The agreement, however, did not hold as clashes resumed a few weeks later. On December 8th, clashes broke out and escalated quickly, with both parties once again claiming the other had launched the first attack. Attacks included use of heavy weaponry, such as fighter jets and shells. The clashes continued throughout December, causing civilian fatalities and considerable displacement of civilians along the border once more. On the 27th of December, a new ceasefire was implemented, halting the clashes and freezing the frontlines. The parties also agreed to ban further military reinforcement. Although tensions remained despite the agreement, clashes halted for the remainder of the year.
During 2025, UCPD recorded 252 fatalities in the conflict between Thailand and Cambodia, with Cambodian soldiers making up more than half. Civilians were also killed, with 51 recorded fatalities in total. The highest estimate for all the conflict’s fatalities during 2025, however, was much higher at 442 fatalities.
Negotiations: YES
Comment on Negotiation: A ceasefire was negotiated, and implemented on the 28th of July.
On October 26th the Cambodian and Thai governments signed the Kuala Lumpur Peace Accord. The parties reiterated their commitment to peace, refrainment from use of force, and their respect for international boundaries. They also agreed to the establishment of an observation team consisting of personnel from ASEAN (Association of Southeast Asian Nations) member states, to ensure the implementation and effectiveness of the ceasefire. The parties also agreed to partake in confidence-building measures, aiming to restore and maintain mutual trust as well as decrease negative public sentiment. Furthermore, they also reaffirmed their commitment to solving the border dispute through peaceful means and international law, and using the established border committees to address such issues. The agreement was signed by both the governments of Thailand and Cambodia, as well as Malaysia and the United States who were present as witnesses.
After clashes had resumed again, a new ceasefire was brokered and implemented on the 27th of December
Third party involvement: YES
Third party involvement names: Government of Malaysia
Government of the United States
Comment on Third Party Involvement: Both signed the agreement in October as witnesses
Victory: NO
Terminated: NO
Type of termination: Not terminated
