The Cambodia–Thailand border dispute is a territorial dispute between Cambodia and Thailand over certain areas of their border. It began in the 1950s, shortly after Cambodia's independence from France, and first centred on ownership of the Preah Vihear temple. The case was brought to the International Court of Justice (ICJ), who decided in 1962 in favour of Cambodia. The issue became dormant over the following decades as Cambodia fell into civil war, but remained unresolved as sections of the countries' borders were never jointly demarcated. The dispute erupted into open conflict in 2008, following Cambodia's nomination of the temple as a UNESCO World Heritage Site and Thai protesters pushing their government over the issue. The clashes led to a request for interpretation from the ICJ to clarify the 1962 ruling, which was decided in 2013. During this round of conflict, disputes also arose over other overlapping border areas, including those around the ancient Khmer temples of Prasat Ta Muen Thom and Prasat Ta Krabey. The conflict subsided for over a decade until it erupted again in 2025, with the worst fighting since the dispute began.
The dispute mostly stems from the Franco-Siamese treaties of 1904 and 1907, which defined the final boundary between Siam (as Thailand was then known) and French Indochina, the borders of which were inherited by Cambodia. While the treaty defined the relevant segment of the boundary along the watershed line of the Dangrek Mountains, demarcation of the border by French surveyors produced maps that deviated from the line in the now-disputed areas, including around the Preah Vihear temple. While Thailand argued at the ICJ that it never approved the maps and that the temple's location on a cliff, more accessible from the Thai side, indicated that it was on Thai territory, the ICJ decided in favour of Cambodia largely based on the fact that Siam never officially protested the map or claimed ownership of the temple while it was under French control. Cambodia also views itself as having rightful claims to the temples due to closer cultural affinity as successor to the Khmer Empire.