U.S. and Afghan military leaders sign certificates officially transferring the UH-60 Black Hawk helicopters from the U.S. military to the Afghan Air Force during a ceremony Oct. 7, 2017, at Kandahar Airfield, Afghanistan. The AAF received Black Hawks from the U.S. to bolster their air power capabilities. The helicopters provide sustainable, capable replacements for aging aircraft currently in use. (U.S. Air Force photo by Staff Sgt. Benjamin Gonsier)