Complex sentence: An anonymous U.S. military official said that an AC-130 gunship was providing air support at the time to defend U.S. special operations troops from Taliban attacks; the U.S. is investigating whether that plane was responsible for the bombing.
Split into simpler sentences: An anonymous U.S. military official said that an AC-130 gunship was providing air support at the time to defend U.S. special operations troops from Taliban attacks. The U.S. is investigating whether that plane was responsible for the bombing.