Soldiers from the 82nd Airborne Division from Fort Bragg , North Carolina, inspect equipment as part of Immediate Response Force training Feb. 1, 2020 at Joint Base Charleston, South Carolina. The IRF is a rapid reaction force jointly maintained by the United States Army and United States Air Force. The purpose of the IRF movement at Joint Base Charleston was to project ready forces, available to deploy at any given moment. Approximately 4,000 soldiers and Air-men participated in the training.