The decision comes just weeks after Africa Command discounted reports civilians, including children, had been killed.
It was not immediately clear how many al-Shabab fighters may have been killed.
A U.S. official says the Pentagon has received permission from the government of Niger to begin flying armed drones.
Defense Secretary Jim Mattis gave his conditional approval to a new authorization for the use of military force. Read more.
U.S. military investigators found more remains of the Army soldier killed in Niger, the Defense Department announced Tuesday.