BEIRUT — Syrian warplanes mounted around a dozen airstrikes on Raqqa, the city held by Daesh (the so-called IS) on Thursday, activists reported, in an unusually heavy attack by government forces on an area also being targeted by a US-led coalition. Activist group Raqqa is Being Slaughtered Silently said on its Twitter feed that “regime jets” had mounted more than 12 raids on the city, which is a major base for Daesh in Syria, and listed eight targets. “There is news about a large number of martyrs and wounded,” it said. The Syrian Observatory for Human Rights said jets believed to belong to the Syrian military had mounted at least 11 airstrikes. — Reuters