Syrian army jets carried out at least 25 air strikes on the Islamic State-held city of Palmyra on Friday, September 18, a group monitoring the war said, according to Reuters.

This was the second intense bombardment of territory held by the militants in two days.

The Syrian Observatory for Human Rights said it was one of the most sustained government bombardments on Palmyra. It came a day after Syrian jets heavily bombed Islamic State’s bastion in the north, the city of Raqqa.

Palmyra, in central Syris and home to vast Roman-era ruins, was seized by Islamic State insurgents from government forces.