6-132. Corps commanders employ security forces to their front and flanks to provide additional security for divisions and BCTs in the MBA. These security forces perform a cover, guard, or screen task depending on the mission variables. Usually the corps employs a defensive covering force in front of MBA divisions. This covering force is a combined arms force task organized to operate forward out of supporting range of the corps’ MBA divisions (the protected force). The corps commander assigns the covering force an AO with enough depth to allow sufficient room to maneuver and to force the enemy to reposition its artillery and air defense systems prior to attacking into the MBA. Enemy repositioning of artillery and air defense artillery (ADA) indicates the enemy main effort, makes those systems vulnerable to friendly attacks in depth, and limits the effectiveness of enemy massed artillery fires.