U.S. Air Force Airmen assigned to the 435th Contingency Response Group and U.S. Army Soldiers assigned to the 173rd Infantry Brigade Combat Team secure the airfield after the arrival of additional 435th CRG Airmen during exercise Swift Response 21 at Cheshnegirovo Airfield, Bulgaria, May 12, 2021. In support of the National Defense Strategy and NATO deterrence objectives, Swift Response 21 built strategic readiness by mobilizing and deploying forces, sustaining them in a training environment and redeploying them when their mission is complete. (U.S. Air Force photo by Senior Airman John R. Wright)