U.S. Army Soldiers with the 2-501st General Support Aviation Battalion (GSAB), 1st Armored Division, based in Ft. Bliss, Texas, conduct pre-flight checks on their HH-60M MEDEVAC Blackhawk during Guardian Response 18 at Camp Atterbury, Ind., April 18, 2018. More than 4,500 Soldiers from across the country are participating in Guardian Response 18, a multi-component training exercise to validate U.S. Army units’ ability to support the Defense Support of Civil Authorities (DSCA) in the event of a Chemical, Biological, Radiological, and Nuclear (CBRN) catastrophe. (U.S. Army Reserve photo by Staff Sgt. Christopher J. Sofia, 78th Training Division)