Denied their Iraqi and Afghan bases by Western intervention, al-Qaeda militants are now flocking into Syria from Libya and Iraq, and are probably responsible for some of the recent terrorist atrocities in Aleppo and Homs. Al-Qaeda’s move to the Levant also threatens to spark a momentous confrontation between Sunni radicals – some of whom have recently taken control of part of the Syrian-Lebanese border – and the Shia Hezbollah in Lebanon.