U.S. Army Gen. John F. Campbell, left front, commander of NATO’s Resolute Support mission and U.S. Forces – Afghanistan, greets U.S. Defense Secretary Ash Carter on Forward Operating Base Fenty in Jalalabad, Afghanistan, Dec. 18, 2015. Carter is on a weeklong trip to the Middle East to meet with defense leaders and thank U.S. and coalition troops for their service and sacrifice, especially during the holiday season. U.S. Air Force photo by Staff Sgt. Tony Coronado