French Prime Minister Bernard Cazeneuve on Thursday warned troops stationed in Africa's Sahel region that they should "prepare for a long war" against jihadists.
He also promised Chad, where French troops have been stationed since 2014 under Operation Barkhane, his nation's financial support.
The operation covers Mauritania, Mali, Niger, Burkina Faso, and Chad.
America's AFRICOM is also working the problem.