Smoke Cover Attack U.S. soldiers conduct an attack drill through smoke as part of exercise Immediate Response 16 at the armed forces training area in Slunj, Croatia, Sept. 14, 2016. The soldiers are assigned to the Minnesota Army National Guard’s 2nd Battalion, 135th Infantry Brigade. The brigade-level exercise uses computer-assisted simulations and field training in Croatia and Slovenia. Army photo by Staff Sgt. Opal Vaughn SHARE: Download: Full Size (0.45 MB) Credit: Staff Sgt. Opal Vaughn VIRIN: 160914-A-MM054-013A.JPG Photo Gallery