Thailand–Cambodia Border Tensions: Strategic Geography, ASEAN Constraints, and Regional Stability
The Thai and Cambodian borders have been a theatre fostering uncertainty since colonial times as both the countries indulge in a continuous contest over the authority of historical temples and areas around them, especially the temple in Preah Vihear. However, a catastrophic landmine incident in July 2025, on the border acted as the catalyst for both the countries locking horns with each other ultimately leadings to hundreds of casualties and thousands of displacements. The conflict peaked in late July as countries like the U.S. and China intervened leading to a ceasefire agreement signed in Putrajaya, Malaysia. The arrangement couldn’t hold both the nations for long as war broke out again in December 2025 which was then mitigated through the pressure posed by the international community with a second ceasefire agreement signed on December 27, 2025.
A historical Demarcation of the Border
The historical rivalry between the two countries goes back to the early 1900s when Cambodia was a part of a broader French Indochina and not as large as it is now with the border between Thailand (Known as Siam in 1900s) and Cambodia being further towards the South. The beginning of the early 20th century witnessed a change where a string of Franco-Siamese treaties gradually formulated the expansion of Cambodia’s territory by initiating a northward shift of the boundary between the two countries. The consecutive treaties signed in 1904 and 1907 started reformulating the border with provinces of Battambang, Sisophon and Siem Reap being ceded to the French Indochina. The treaty moved the border northward to follow the Dangrek escarpment. However, this attempt at creating a well-defined border brought three revered Khmer temples (Ta Muen Thom, Prasat Ta Khwai, and Preah Vihear) leaving the ownership open to interpretation with both nations referring to different cartographies.
The 1907 Annex I treaty, which is the foundation for the conflict between the two nations, didn’t initially cause conflict. The conflicts began with Siam’s occupation of the Preah Vihear temple which became a matter of contestation after Cambodia’s independence in 1953. This case was then taken to the International Court of Justice in 1959, which deemed Cambodia’s claims on the temple valid based on the agreement of both parties on the 1907 Annex I map in 1962. However, the ruling wasn’t able to take a firm decision on the areas around the temple which has given precedence to the confrontations persisting even today. The rivalry resurfaced in 2008 when Cambodia registered Preah Vihear Temple as an UNESCO World Heritage Site, strengthening its claim over the area, inviting a violent retaliation from Thailand which caused more than 20 deaths over the next three years. Cambodia reappealed to get a confirmation from the ICJ which mandated the immediate withdrawal of the army in 2012. The court also classified the area around the temple under Cambodian territory.
The Escalation in July 2025
The catalyst to the vehement exchanges between the two countries was a minor confrontation near the Preah Vihear Temple where a Cambodian soldier died. This was followed by Cambodia’s banning Thai goods and Thailand’s restricting all the border crossings and suspending all the internet and power links to Cambodia. Another major hit was the Cambodian leader Hun Sen exposing a recorded conversation with Thailand’s Prime Minister Paetongtarn Shinawatra which led to her suspension by the Constitutional Court.
The situation worsened when a Thai soldier triggered a Landmine injuring five soldiers with him on July 23, 2025. Cambodia was accused for laying new landmines, leading to a deterioration in the diplomatic arrangements. The conflict aggravated over the next few days over various districts close to the border ranging from social media exchanges between the Prime Ministers of the two countries to artillery exchange between the Armies.
Association of the Southeast Nations (ASEAN), led by Malaysia and United Nation Security Council intervened, followed by an announcement by the U.S. President Donald Trump that both the countries have agreed on deliberations. The ceasefire was announced on July 28, 2025 in Putrajaya, Malaysia. However, the agreement was short-lived as relations between two countries deteriorated over the course of next couple of months with Thailand discontinuing with mandate under the ceasefire, accusing Cambodia of laying more landmines. The confrontation escalated including air strikes, killing more than 30 civilians by end-December. This was brought to a halt with a ceasefire agreement brokered by China which was initially mandated for a 72-hour period, but later extended with Thailand releasing Cambodian captives.
Implications and Inferences
The major implications of the so called “Lawfare” between the two countries have been reflected in the trading, domestic, and international sectors drastically. A significant amount of revenue was lost in tourism and trade of everyday items which afflicted the global supply chain. The geographical implications remain significant as a skirmish near the Malacca strait which is considered one of the major trade routes had created an environment deemed uncertain for trade. Moreover, this rivalry over the course of the last couple of decades have proven to be a humanitarian disaster, with hundreds of people dying and millions displaced. There were a few more paradigms, requiring immediate addressal and a gradual change, that stood pivotal in the geopolitical condition prevailing in the Asia-Pacific region, namely, the hegemonic interference and an alarming ASEAN approach.
The Hegemonic Power Struggle in the Background
The conflict between Cambodia and Thailand exposed how a broader hegemonic struggle interferes in the skirmish between the peripheral nations. This was seen as the American President became a significant part of the Joint Peace Statement signed by Thailand and Cambodia. While China wasn’t considered a part of the diplomatic talks and the peace brokered by the two countries, President Xi Jinping made a public statement confirming their role in the brokered peace and their interest at publicising their efforts. The disturbances between Thailand and Cambodia were crucial for both China and the U.S. Cambodia stand as an ally of China and the choking of the Malacca Strait could have severe repercussions for Chinese trade. Moreover, both the superpowers have been attempting at building credibility to expand soft power diplomacy.
There were different approaches employed by both the countries. While America took oppressive policy measures suspending all talks for tariff reduction until an arrangement was considered by both Thailand and Cambodia, China took a quieter diplomatic approach, emphasising on de-escalation through the informal trilateral consultation and Foreign Minister Wang Yi’s separate meetings with Thai and Cambodian ministers. While a coincidentally cumulative action taken by both the superpowers led to a required de-escalation, it also exposed cracks in the regional autonomy of the Association of Southeast Asian Nations (ASEAN).
The ASEAN way
ASEAN, that has propagated neutrality and centrality in the region found itself questioned as the confrontation highlighted intricacies in the regional governance of ASEAN and its limitations. The rivalry had been active for decades with activities across the border being evident for two months before it escalated into a full-scale war leaving ASEAN ample time to intervene. Cambodia’s pivot to ICJ in 2011 instead of raising the issue in the ASEAN conferences reflects on the lack of trust that the countries have on the crisis prevention structure of ASEAN. This was also exposed as the ASEAN Secretary-General Kao Kim Hourn admitted the escalation being a “surprise” for the bloc.
While, the ceasefire was signed in Malaysia (ASEAN Chairmanship 2025) the major credit of de-escalation was given to the American intervention and the Chinese efforts at mediation. Moreover, the re-escalation in November and December raised questions on the authority of the bloc as well. Therefore, even after ASEAN’s policy of centrality and a propagated approach of avoiding the major geopolitical power struggle, the lack of speed and enforcement capacity of the bloc leaves space for the Hegemonic contenders to interfere and project their interests on the Southeast Asian nations.
The Way Forward
The uncertainty still vacuums the environment pertaining in both the countries. The war might not have resumed but there have continuous threats of re-escalation as witnessed on January 6, 2026 which raised concerns as Thai army claimed new border strikes, deemed as an accident by Cambodia.
The situation requires urgent attention of the International Court of Justice, and the ASEAN, to come to a conclusion that is respected both the parties. ASEAN, under Philippines’ chairmanship looks forward to create a peaceful environment as it mentions people’s empowerment as one of the crucial pillars of the ASEAN 2026 mandate. It also stands significant as ASEAN’s credibility hangs in the balance.
China will also keep a close watch at the conflict as Cambodia remains one of its allies, and any escalation directly afflicts the operations in the Malacca strait posing a threat to Chinese trade. An unstable political environment in Thailand and the exposed scam compounds in Cambodia scream the need for a more inward-looking approach, which makes this ceasefire an opportunity for both the countries.
References
1. Pradnyana, Hadi. "The Limits of the ASEAN Way: Reflections on Cambodia–Thailand Peace Talks." Modern Diplomacy, October 25, 2025. https://moderndiplomacy.eu/2025/10/25/the-limits-of-the-asean-way-reflections-on-cambodia-thailand-peace-talks/.
2. "A Visual Guide to the Historical Maps and Temples at the Heart of the Thailand-Cambodia Conflict." The Guardian, December 17, 2025. https://www.theguardian.com/world/2025/dec/17/a-visual-guide-to-the-historical-maps-and-temples-at-the-heart-of-the-thailand-cambodia-conflict.
3. Teekah, Ethan. "Thailand-Cambodia Conflict." Encyclopedia Britannica, December 31, 2025. https://www.britannica.com/event/Thailand-Cambodia-Conflict.
4. Ma, Bo, and Zining Xu. "Mediation with Chinese Characteristics in the 2025 Thailand–Cambodia Border Crisis." East Asia Forum, December 16, 2025. https://eastasiaforum.org/2025/12/16/mediation-with-chinese-characteristics-in-the-2025-thailand-cambodia-border-crisis/.
5. Banerjee, Sreeparna, and Abhishek Sharma. "Fault Lines Exposed: Cambodia Dispute Triggers Political Turmoil in Thailand." Observer Research Foundation, July 1, 2025. https://www.orfonline.org/expert-speak/fault-lines-exposed-cambodia-dispute-triggers-political-turmoil-in-thailand.
6. Geopolitical Analyst Asia-Pacific. "Cambodia-Thailand Border Clashes and Their Impact on China." SpecialEurasia, December 13, 2025. https://www.specialeurasia.com/2025/12/13/cambodia-thailand-china-clashes/.
7. Head, Jonathan, and Joel Guinto. "Thailand and Cambodia Agree to 'Immediate Ceasefire'." BBC News, July 28, 2025. https://www.bbc.com/news/articles/c5yl9l60e3no.
(The views expressed are those of the author and do not represent the views of CESCUBE)
Photo by SAM sokkolinmony on Unsplash
