For decades, temples have been a source of conflict in border disputes between Cambodia and Thailand, with each laying claim to centuries-old worship sites perched on the mountains that divide the two nations.

Prasat Preah Vihear and Prasat Ta Muen Thom, both Khmer-era Hindu temples about 95 miles apart, are two of the key sites where tensions flared on Thursday. For years, disputes over the sacred sites have stoked nationalistic fervor on both sides.

Prasat Ta Muen Thom was constructed in the 12th century with laterite — a reddish, porous stone — and comprises a wide set of archaeological sites nearby. The temple, accessible from both sides, is in a poorly demarcated part of the border and stands as an important religious and cultural site for both Cambodians and the Thai. Troops from both countries constantly patrol the temple’s area, leading to frequent skirmishes.

In February, the ancient site was temporarily closed after a group of Cambodians sang a nationalist song near the site, The Khmer Times, a Cambodian news outlet, reported.

Hun Sen, Cambodia’s de facto leader, alleged in a social media post that a Thai military commander had “started this war” by ordering the closure of the temple on Wednesday and opening fire on Cambodian troops on Thursday.

The area around Prasat Preah Vihear, a network of sanctuaries, has been where many of the most deadly and high-profile clashes have occurred in past years. In 2011, at least 20 were killed and thousands displaced near the holy site as troops opened fire from both sides.

In 1962, the International Court of Justice ruled that Prasat Preah Vihear fell within the sovereignty of Cambodia. Thailand rebuked the ruling, which cited French colonial maps placing the site in Cambodia.

Amid simmering tensions, Cambodia made a successful bid to designate the temple a UNESCO World Heritage Site in 2008, reigniting hostilities.

In 2013, the I.C.J. reasserted Cambodia’s claim to the temple, ordering Thai forces to vacate the area, but Thailand again rejected the ruling.

The Khmer Times reported on Thursday that Thailand had conducted airstrikes on the Preah Vihear ruins. Cambodia’s culture ministry said that the Preah Vihear temple had sustained “significant damage” and blamed Thailand.

“The destruction of Preah Vihear Temple is both a cultural disaster and a moral tragedy,” the ministry said.