A spate of US airstrikes against mosques commandeered by the Islamic State (IS) in Syria appear to point to the Donald Trump administration adopting unusual measures to target extremists, experts say.

The Pentagon acknowledged Monday that coalition fighter jets struck two mosques near Susah, Syria, following reports of six civilian deaths in the bombing of a religious school in Hajin, a town in the Euphrates River Valley. The US-led coalition fighting the Islamic State conducted a third mosque strike Wednesday, a military spokesman said.

US military officials said they approved the strikes because the militants had converted the sanctuaries into battlefield control nodes. “It’s not us, it’s IS that turned that mosque into a command-and-control center, which made it a legitimate military target,” Pentagon spokesman Rob Manning told reporters Monday.

A Pentagon strike on a mosque would typically take considerable planning. The Defense Intelligence Agency has a no-strike list to protect noncombatants on battlefields where US warplanes are active. But the Pentagon can overturn those protections if it determines that militants are using schools, hospitals or religious buildings to target US troops.