Assad on the back foot

FOR the rebels fighting against President Bashar Assad, it was a huge victory. On March 28th a collection of Islamist fighters, including Jabhat al-Nusra, an al-Qaeda affiliate, captured the city of Idleb. Long contested, it is only the second big one to fall to the rebels in four years of war. The first, Raqqa, was snatched by the jihadists of Islamic State (IS), who made it the capital of their caliphate. Only three days before the rebels won Idleb, they took Bosra, a town in southern Syria famous for its second-century Roman amphitheatre.