Four Moroccan truck drivers who were kidnapped in West Africa over the weekend were released in Niger, officials said. The drivers were the latest victims of insecurity in the Sahel, an arid swath of land south of the Sahara where militant groups such as the Islamic State Sahel Province have in recent years exploited local grievances to grow their ranks and expand their presence.

Four Moroccan truck drivers went missing on Saturday as they crossed the restive border area between Burkina Faso and Niger, according to a source from the Moroccan embassy in Burkina Faso and a Moroccan transport union.