Retired service members salute during the National Anthem at the Vietnam War Pilots and Aircrew Memorial Tree Dedication Ceremony on Arlington National Cemetery, Va., Aug. 28, 2015. The Memorial service was hosted by the Vietnam Helicopter Pilots Association and honored the thousands of men and women who perished during the "Helicopter War." (U.S. Air Force photo by Staff Sgt. Chad C. Strohmeyer) (Released)