Hundreds of suspected Boko Haram fighters have been killed since January 31 as Chadian forces, backed by Nigerian and French aircraft, overran the jihadist group’s strongholds in northern Nigeria. The latest outbreak of fighting occurred after members of Boko Haram ambushed Chadian forces who had been staging in nearby Cameroon. On Wednesday, hundreds of Boko Haram fighters driven out of Gamboru crossed the border and attacked Chadian military posts in Fotokol, in far northern Cameroon, residents and military officers said. Cameroonian forces are assisting Chadian forces in countering the Boko Haram assault in Fotokol, and fighting remains ongoing. In late January, Chadian forces countered a Boko Haram ambush near Malam Fatori and reportedly killed 120 insurgents, according to regional reports.