U.S. paratroopers assigned to Able Company, 2nd Battalion, 503rd Infantry Regiment, 173rd Infantry Brigade Combat Team (Airborne), prepare to breach a perimeter using explosives during a live fire exercise, a part of exercise Rock Proof in Postojna, Slovenia, April 28, 2014. Sky Soldiers are here for a two week training exercise with their partners from the Slovenian army’s 10th Battalion. (photo by U.S. Army Staff Sgt. Pablo N. Piedra / released)