Lt. Col. Christopher Wilson, commander of 121st Fighter Squadron, District of Columbia Air National Guard, preforms pre-flight checks prior to departing for Green Flag 21-06 at Nellis Air Force Base, Nev., April 14, 2021. Green Flag provides combat training to joint and coalition warfighters in air-land integration and the joint employment of air power in support of the U.S. Army’s National Training Center at Fort Irwin, Calif.