For the first time, USAF sends the RQ-1 Predator remotely piloted aircraft on flights in a combat zone, flying reconnaissance over Serbia during Allied Force. (The Army employed the ACTD Predator over Bosnia for Deliberate Force in 1995.)
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.

