An aerial view of Muscatatuck Urban Training Center during Vibrant Response 14. Vibrant Response 14 is a major field training exercise conducted by U.S. Northern Command and led by U.S. Army North. U.S. Army North conducts Vibrant Response 14 to confirm the operational readiness and tactical capabilities of major elements of the Department of Defense's specialized forces designed to respond to chemical, biological, radiological and nuclear (CBRN) incidents in support of local, state and federal civilian agencies.