U.S. Marines with the Provost Marshal’s Office, Security and Emergency Battalion, Marine Corps Base Camp Pendleton, respond to a simulated active shooter drill in support of exercise Semper Durus 23 on Camp Pendleton, California, April 11, 2023. Semper Durus is a regional command post exercise designed to improve regional command and control, enhance interagency coordination, and improve installation capabilities to respond to, and recover from, a crisis event and validate the installation mission assurance all-hazard plan. (U.S. Marine Corps video by Sgt. Jared D. Curtis)