Music superstar Toby Keith on his fifth USO tour to the Persian Gulf and Germany to entertain the troops in 2007. (Dave Gately/USO)The Arleigh Burke-class guided-missile destroyer USS Oscar Austin (DDG 79) transits the Arctic Circle on Sept. 5, 2017. (MC2 Ryan U. Kledzik/Navy)A KC-135 Stratotanker from the 127th Wing Air Refueling Group, Selfridge Air National Guard Base, Mich., escorts five of the U.S. Air Force Thunderbirds F-16s to a performance at the Selfridge Centennial Open House and Air Show on Aug. 17, 2017. (Master Sgt. David Kujawa/Air National Guard)Air Force Senior Airman Sean Harris, 44th Aircraft Maintenance Unit weapons load team member, inspects the connection between a belt of M-61A1 cannon rounds and an F-15 Eagle during an exercise Sept. 6, 2017, at Kadena Air Base, Japan. (Senior Airman Quay Drawdy/Air Force\)Sgt. Samiera Lanier, a soldier assigned to 48th Chemical Brigade, 2nd Chemical Battalion, is greeted by a young child after arriving at Liberty Fire Department in Liberty, Texas, on Sep. 2, 2017. She and other military personnel are working with civil authorities in the aftermath of Hurricane Harvey. (Spc. Dustin D. Biven/Army)