Gen. John Jumper, Air Force Chief of Staff, authorizes deactivation of the Peacekeeper ICBM, originally designed to carry 10 independently targeted warheads.
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.

