Army Maj. Brian Casey, center, and Spc. Michael Lee, provide medical aid to a mock patient in a medical tent during Guardian Response 18 at Muscatatuck Urban Training Center, Ind., April 12, 2018. Casey is a field surgeon and Lee is a combat medic assigned to the 251st Area Support Medical Company. An Army total force exercise, Guardian Response allows active duty, Guard and reserve soldiers to work together to respond effectively to a chemical, biological, radiological, nuclear scenario. Army Reserve photo by Staff Sgt. Carolyn Hawkins