U.S. Air Force Honor Guardsmen hold a flag during flag folding ceremony in honor of Capt. Glenn Cook in front of the Vietnam Veteran’s Memorial in Washington, D.C., May 19, 2015. Cook’s plane was shot down near Nha Trang, Vietnam, Oct. 21, 1969. His remains were never found. (U.S. Air Force photo/Senior Airman Joshua R. M. Dewberry)