Marines with 1st Battalion, 4th Marine Regiment and 3d Assault Amphibian Battalion,1st Marine Division, I Marine Expeditionary Force, check their communication connections during a scenario-based, battalion-sized amphibious landing exercise for Exercise Iron Fist 2016, Feb. 26, 2016. Iron Fist is an annual, bilateral amphibious training exercise designed to improve USMC and JGSDF’s ability to plan, communicate and conduct combined amphibious operations at the platoon, company and battalion levels. - Marines with 1st Battalion, 4th Marine Regiment and 3d Assault Amphibian Battalion,1st Marine Division, I Marine Expeditionary Force, check their communication connections during a scenario-based, battalion-sized amphibious landing exercise for Exercise Iron Fist 2016, Feb. 26, 2016. Iron Fist is an annual, bilateral amphibious training exercise designed to improve USMC and JGSDF’s ability to plan, communicate and conduct combined amphibious operations at the platoon, company and battalion levels.