Paratroopers from 1st Battalion, 503rd Parachute Infantry Regiment (PIR), 173rd Infantry Brigade Combat Team (Airborne) dismount a UH-60 Blackhawk helicopter to pull security as part of exercise Immediate Response 19 at Udbina Airbase, Croatia, May 17, 2019. The U.S. forces presence and commitment to the defense of its allies are important symbols of assurance and provide deterrence against potential adversaries.