U.S. Marines with 3rd Battalion, 7th Marine Regiment, load sandbags onto a truck during Adversary Force Exercise 5-23 at Marine Corps Air-Ground Combat Center, Twentynine Palms, California, Aug. 9, 2023. AFX 5-23 tested the skills of Marines in seizing and maintaining a combat presence in urban environments by training in offensive and defensive tactics, conducing logistics in a contested environment, and utilizing mechanized infantry. - U.S. Marines with 3rd Battalion, 7th Marine Regiment, load sandbags onto a truck during Adversary Force Exercise 5-23 at Marine Corps Air-Ground Combat Center, Twentynine Palms, California, Aug. 9, 2023. AFX 5-23 tested the skills of Marines in seizing and maintaining a combat presence in urban environments by training in offensive and defensive tactics, conducing logistics in a contested environment, and utilizing mechanized infantry.