GREAT LAKES, Ill. (Feb. 7, 2023) Sailors and civilian police assigned to Naval Station Great Lakes security forces respond to a simulated active shooter as part of exercise Citadel Shield-Solid Curtain 2023 at the National Museum of the American Sailor near the main gate at Naval Station Great Lakes, Feb 7, 2023. Exercise Citadel Shield-Solid Curtain 2023 is a two-part, anti-terrorism force protection exercise that is being conducted nationwide on Navy installations, Feb. 6-17. The annual exercise is not in response to any specific threat, but is used to evaluate the readiness of fleet and installation security programs. (U.S. Navy photo by John Sheppard)