Robert Fowler, a senior Canadian diplomat, was held hostage for five months by Al Qaeda in Niger in 2009. He says that since his capture and release, terror attacks and events in the region, such as the brief Islamist takeover of northern Mali, should serve as a wake-up call of a jihadist danger. He believes militants aim to set up a seven thousand kilometre Islamic caliphate stretching from Mauritania to Somalia. Is he scaremongering, or does he have a point?