THIES, Senegal (AP) — The only place in the world where fighters linked to al-Qaida and the Islamic State group are cooperating is in West Africa’s sprawling Sahel region, giving the extremists greater depth as they push into new areas, according to the commander of the U.S. military’s special forces in Africa. “I believe that if it‘s left unchecked it could very easily develop into a great threat to the West and the United States,” U.S. Air Force Brig. Gen. Dagvin Anderson told The Associated Press in an interview this week. The leader of U.S. Special Operations Command Africa described...