The U.S. military official with knowledge of the ambush investigation said that it increasingly appears that the soldiers' mission did change after they left their base in the capital, Niamey. The unit, the official said, apparently was rerouted to help another military team target a top Islamic State militant named Dadou, who was code-named "Naylor Road" by the U.S. military. But bad weather prevented the commandos from reaching the area. The unit continued to search for the militant and his fighters and eventually spent the night on the border, he said.