An engineer held hostage for 11 months by armed Islamists in Nigeria has returned to France, accompanied by Foreign Minister Laurent Fabius. The kidnapping was claimed by Ansaru, a split-off from the Boko Haram movment. Marc-Antoine Perouse de Montclos, the author of a forthcoming book titled Boko Haram: Islamism, Politics, Security, and the State in Nigeria, comments.