Pacific Air Forces (PACAF) is established, succeeding the Far East Air Forces, composed of the 5th Air Force, 13th Air Force, and 20th Air Force. Headquarters are moved to Hickam Air Force Base, Hawaii.
The U.S. began extensive air and artillery strikes against Islamic State group targets in Syria on Dec. 19 in retaliation for the killing of three Americans on Dec. 13 by a gunman affiliated with ISIS, U.S. officials said.

