Leads, manages, supervises, and performs security force (SF) activities, including installation, weapon system, and resource security; antiterrorism; law enforcement and investigations; military working dog function; air base defense; armament and equipment; training; pass and registration; information security; and combat arms.

The riflemen employ the M16A2 service rifle, the M203 grenade launcher and the squad automatic weapon (SAW). Riflemen are the primary scouts, assault troops, and close combat forces available to the MAGTF. They are the foundation of the Marine infantry organization, and as such are the nucleus of the fire team in the rifle squad, the scout team in the LAR squad, scout-snipers in the infantry battalion, and reconnaissance or assault team in the reconnaissance units. Noncommissioned officers are assigned as fire team leaders, scout team leaders, rifle squad leaders, or rifle platoon guides.

The mortarmen is responsible for the tactical employment of the 60mm light mortar and the 81mm medium mortar. Mortarmen provide indirect fire in support of the rifle and LAR squads/platoons/companies and the infantry and LAR battalions. They are located in the weapons platoons of the rifle and LAR companies and the weapons company of the infantry battalion. Noncommissioned officers are assigned as mortar gunners, forward observers, fire direction plotters, and squad and section leaders.