A Syrian opposition leader called on world leaders to take “immediate action” to end government attacks on rebel-held suburbs of Damascus, amid reports that some 150 people have been killed in government airstrikes in the past 10 days.

The heinous acts committed by Islamic State are done to make it look more powerful and impenetrable. But they can also unite its enemies and detractors, writes Arie W Kruglanski.

Islamic State said yesterday that an American woman hostage it was holding in Syria was killed when Jordanian fighter jets bombed a building where she was being held, but Jordan expressed doubt about the Islamist militant group’s account of her death.

Muslim clerics widely denounced Islamist militants in Syria over the burning to death of a Jordanian pilot, saying such a form of killing was considered an abomination under Islam, no matter the justification.