Marine Monitors Marines monitor an unmanned aircraft during exercise Steel Knight 2019 at Marine Corps Air Ground Combat Center, Twentynine Palms, Calif., Dec 4. 2018. The annual exercise helps Marines and sailors enhance tactical and combat readiness skills. SHARE IMAGE: Download Image: Full Size (1.36 MB) Tags: Marine Corps Photo By: Marine Corps Sgt. Kyle Talbot VIRIN: 181204-M-ZX256-1014X.JPG Photo Gallery