Marines from the Chemical/Biological Incident Response Force out of Indiana Head, Maryland run a decontamination tent assisting simulated victims of a nuclear detonation in exercise Vibrant Response at Muscatatuck Urban Training Center in Southern Indiana July 29. The exercise, hosted by U. S. Army North, U. S. Northern Command's Joint Force Land Component Command, brings together approximately 9,000 military and civilian personnel from across the country to simulate the response to a terrorist attack in the United States.