The Syrian Observatory for Human Rights, a monitoring group based in Britain, said the airstrike, which hit a camp in Kafr Jina, was the third time in 48 hours that Turkish warplanes had struck pro-government forces in Afrin.

The Syrian Democratic Forces, a Kurdish-led, United States-backed alliance, said in a statement that Turkish airstrikes had targeted positions held by the Syrian Army’s “popular forces” from 5 a.m. to 10 a.m.