Legions of ISIS foreign fighters have fanned out across the globe to pose the threat of a resurgence by the group in territories from Syria into Asia.

With monikers as divergent as the “Professor” and the “Destroyer”, the Islamic State group’s new head has a reputation for brutality, but otherwise remains largely an enigma.

A whistle-blower has claimed that he earned tens of thousands of euros from Qatar for hiding a dossier that documented the country’s support for Hezbollah.