An aircraft electrical and environmental systems specialist assigned to the 555th Aircraft Maintenance Unit loosens screws on a U.S. Air Force F-16 Fighting Falcon at Graf Ignatievo Air Base, Bulgaria, July 9, 2021. Eight F-16s assigned to the 555th Fighter Squadron are participating in exercise Thracian Star 21, a multilateral training exercise with the Bulgarian air force, aimed to enhance the ability to rapidly deploy to remote locations and provide a credible force to assure stability for the region. (U.S. Air Force photo by Airman 1st Class Brooke Moeder)