U.S. Air Force F-16 maintainers, assigned to the Air National Guard’s 169th Fighter Wing from McEntire Joint National Guard Base, S.C., perform post-flight duties on a jet that returned from a morning mission as the third and final week of air operations continue in support of Arctic Challenge Exercise 2019 at Kallax Air Base, Luleå, Sweden, June 3, 2019. ACE 19 is a Nordic aviation exercise that provides realistic, scenario-based training to prepare forces for enemy defensive systems. U.S. forces are engaged, postured and ready to deter and defend in an increasingly complex security environment. (U.S. Air National Guard photo by Senior Master Sgt. Edward Snyder)