A B-1 Bomber takes off from Ellsworth Air Force Base, S.D., to participate in Green Flag exercise 18-1 on Oct. 18, 2017. Green Flag is a joint training exercise held 10 times a year at Nellis Air Force Base, Nev. that tests aircrew and maintainer’s warfighting capabilities. (U.S. Air Force photo by Airman 1st Class Thomas Karol)