Multi-nation aircraft maintainers from Great Britain, United States and Sweden, gather to compare maintenance procedures of their respective fighter aircraft during Arctic Challenge Exercise 2019 at Kallax Air Base, Luleå, Sweden, May 23, 2019. ACE 19 is a Nordic aviation exercise that provides realistic, scenario-based training to prepare forces for enemy defensive systems. Interoperability and combined training during exercises like ACE 19 enhances professional relationships and improves overall coordination with allies and partner militaries. (U.S. Air National Guard photo by Senior Master Sgt. Edward Snyder)