U.S. Air Force Airmen don protective gear during a simulated chemical attack on Seymour Johnson Air Force Base, N.C., Jan. 16, 2013. The simulated attack was one of several during Phase II of Coronet Warrior 13-01, testing airmen's ability to survive and operate in a deployed environment. (U.S. Air Force photo/Airman 1st Class Mariah Tolbert/Released)