BANGKOK, Thailand (AFP) — Thailand launched air strikes on Cambodian military targets on Thursday as Cambodia fired rockets and artillery, killing a civilian, in a dramatic escalation of a long-running border row between the two neighbors.

The neighbors are locked in a bitter spat over an area known as the Emerald Triangle, where the borders of both countries and Laos meet, and which is home to several ancient temples.

The squabble has dragged on for decades, flaring into bloody military clashes more than 15 years ago and again in May, when a Cambodian soldier was killed in a firefight.

The conflict blazed up on Thursday, with Cambodia firing rockets and artillery shells into Thailand and the Thai military scrambling F-16 jets to carry out air strikes.

Six jets were deployed from Ubon Ratchathani province, hitting two “Cambodian military targets on the ground,” according to Thai military deputy spokesperson Ritcha Suksuwanon.

The Thai prime minister’s office said a Cambodian artillery shell hit a house over the border, killing one civilian and wounding three others, including a five-year-old child.

Both sides blamed the other for starting the fighting, which erupted near two temples on the border between the Thai province of Surin and Cambodia’s Oddar Meanchey.

“The Thai military violated the territorial integrity of the Kingdom of Cambodia by launching an armed assault on Cambodian forces stationed to defend the nation’s sovereign territory,” defense ministry spokesperson Maly Socheata said in a statement.

“In response, the Cambodian armed forces exercised their legitimate right to self-defense, in full accordance with international law, to repel the Thai incursion and protect Cambodia’s sovereignty and territorial integrity.”

Cambodian Prime Minister Hun Manet requested an urgent meeting of the United Nations Security Council to address what his foreign ministry labeled “unprovoked military aggression.”

Thailand’s government spokesperson, meanwhile, accused Cambodia of being “inhumane, brutal and war-hungry,” and Bangkok’s foreign ministry said all border crossings had been shut and nearby residents evacuated.