Master Sgt. Travis Greenwell, an Airman from the Kentucky Air National Guard’s 123rd Contingency Response Group, responds to a simulated attack after donning a chemical warfare ensemble at Amedee Army Airfield, Calif., Aug. 25, 2024, as a part of a U.S. Transportation Command exercise to revalidate the 123rd CRG’s capability to lead a Joint Task Force-Port Opening. JTF-PO is a joint mission designed to safely and effectively distribute cargo and supplies to austere areas affected by catastrophic events or conflict. Contingency response units must be re-certified to execute the mission every three years. (U.S. Air National Guard photo by Master Sgt. Joshua Horton)