CHEMICAL ATTACK EXERCISE U.S. airmen take cover during a simulated bombing and chemical attack as part of an operational readiness exercise on Royal Air Force Base Mildenhall, England, Sept. 11, 2012. The airmen are assigned to the 100th Civil Engineer Squadron. SHARE: Download: Full Size (0.08 MB) Credit: VIRIN: 800265-S-KSH08-543.jpg Photo Gallery