U.S. Air Force Master Sgt. Robert Green, second from right, assigned to the 145th Security Forces Squadron, North Carolina Air National Guard, monitors security alongside Secret Service personnel as President Barack Obama arrives aboard Air Force One at the North Carolina Air National Guard base at Charlotte Douglas International Airport in Charlotte, N.C., Aug. 26, 2014. Obama visited Charlotte to deliver remarks during the 96th American Legion National Convention about issues affecting U.S. military veterans.