U.S. Army paratroopers check their protective masks before entering the gas chamber to conduct chemical, biological, radiological and nuclear training at the 7th Army Joint Multinational Training Command's Grafenwoehr Training Area, Germany, March 31, 2015. U.S. Army paratroopers check their protective masks before entering the gas chamber to conduct chemical, biological, radiological and nuclear training at the 7th Army Joint Multinational Training Command's Grafenwoehr Training Area, Germany, March 31, 2015. SHARE: Download: Full Size (4.9 MB) Tags: Photo Essays Credit: VIRIN: 158088-Y-XAV13-268.jpg Photo Gallery