KEY WEST, Fla. (Feb. 1, 2021) Navy security forces perform a sweep of a building during an active shooter training exercise at Naval Air Station Key West during Exercise Citadel Shield. Exercise Citadel Shield-Solid Curtain 2021 is a two-part, anti-terrorism force protection exercise that is being conducted nationwide on Navy installations, Feb. 1-12. The annual exercise is not in response to any specific threat, but is used to evaluate the readiness of fleet and installation security programs. Naval Air Station Key West is the state-of-the-art facility for combat fighter aircraft of all military services, provides world-class pierside support to U.S. and foreign naval vessels, and is the premier training center for surface and subsurface military operations. (U.S. Navy photo by Trice Denny)