Marines with 3rd Battalion, 25th Marines, 4th Marine Division, secure an entrance into the hostile trenches at Range 400 during Integrated Training Exercise (ITX) 4-21 at Marine Corps Air Ground Combat Center Twentynine Palms, California on July 23, 2021. ITX is the culmination of Marine Forces Reserve units’ training cycle as they participate in a live-fire, combined arms exercise as a part of an integrated Marine Air Ground Task Force. (U.S. Marine Corps photo by Lance Cpl. David Intriago)