Marines with Echo Company, 4th Tank Battalion, 4th Marine Division, dismount their M1A1 Abrams main battle tank to attend a safety brief before an obstacle clearing detachment practical application, during Integrated Training Exercise 4-18, aboard Marine Corps Air Ground Combat Center Twentynine Palms, California, June 12, 2018. The OCD training was conducted to prepare Marines for the execution of a live-fire combined arms breach in which mechanized units will detonate a 1,000 pound mine clearing charge.