Latest "U.S. Central Command" stories
Air Forces Central boss Lt. Gen. Alexus Grynkewich said the balloons haven't encroached on "sensitive" U.S. sites in the Middle East.
The U.S. military says two rockets struck a base housing American troops in eastern Syria without causing any casualties or material losses.
American forces have conducted three raids in eastern Syria and arrested six Islamic State groups militants.
American forces killed two Islamic State group officials on Sunday in a helicopter raid in eastern Syria, U.S. Central Command said.