Thailand has launched air strikes along its disputed border with Cambodia after both sides accused each other of violating a ceasefire agreement brokered by U.S. President Donald Trump, the Thai military said on Monday.

At least one Thai soldier was killed and four others wounded in fresh clashes around two areas of Ubon Ratchathani province after Thai troops reportedly came under Cambodian fire.

“The Thai side has now begun using aircraft to strike military targets in several areas,” the military said in a statement.

Cambodia’s defence ministry said Thai forces carried out dawn attacks at two locations following what it described as days of Thai provocations. It claimed Cambodian troops had not retaliated.

Thailand’s army, however, said Cambodian forces fired BM-21 rockets toward Thai civilian areas, though no casualties were reported.

The latest flare-up comes months after a five-day border conflict in July that left at least 48 people dead and displaced some 300,000 people. A ceasefire was later arranged by Malaysian Prime Minister Anwar Ibrahim and President Trump, followed by an expanded peace deal signed in Kuala Lumpur in October.

Tensions resurfaced last month after a landmine blast maimed a Thai soldier, prompting Bangkok to suspend implementation of the ceasefire pact.

Cambodia’s former longtime leader Hun Sen accused Thailand of aggression and urged Cambodian troops to maintain restraint. “The red line for responding has already been set,” he said on Facebook.

In Thailand, authorities said more than 385,000 civilians across four border districts are being evacuated, with over 35,000 already moved to temporary shelters.

Thailand and Cambodia have disputed parts of their 817-km border for more than a century, with sporadic clashes — including a weeklong artillery exchange in 2011 — despite repeated efforts at peaceful settlement.