A U.S. paratrooper assigned to 1st Squadron, 91st Cavalry Regiment, 173rd Airborne Brigade, fires his M4 carbine with soldiers from the German Armed Forces United Nations Training Centre, during a combined training exercise at the Infantry Training Area in Hammelburg, Germany, Jan. 29, 2015. Soldiers from the allied nations trained on several light-infantry weapons systems during a two-day combined exercise to enhance interoperability. (U.S. Army Photo by Visual Information Specialist Markus Rauchenberger/released)