Switching from the Minuteman III to the Sentinel system, led by Northrop Grumman, involves the replacement of more than 600 facilities across five states.
Two MH-139A Grey Wolf helicopters completed their first operational mission Jan. 8, escorting a Minuteman III intercontinental ballistic missile convoy.
The LGM-35A Sentinel has run into severe cost overruns and schedule delays that could force the Air Force to keep Minuteman IIIs operational years longer.
