U.S. Air Force Airmen assigned to the 633rd Security Forces Squadron participate during the National Police Week opening ceremony at Joint Base Langley-Eustis, Va., May 15, 2017. In 1994, President Bill Clinton signed Public Law 103-322 directing that the flag of the United States be displayed at half-staff on all government buildings on May 15 each year. (U.S. Air Force photo/Staff Sgt. Areca T. Bell)