U.S. service members participate in exercise Vibrant Response 13-2 at the Muscatatuck Urban Training Center in Butlerville, Ind., Aug. 14, 2013. Vibrant Response is a U.S. Northern Command-sponsored field training exercise for chemical, biological, radiological, nuclear and high-yield explosive consequence management forces designed to improve their ability to respond to catastrophic incidents. (U.S. Air Force photo by Airman 1st Class Logan Brandt/Released)