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Common Tactical Concepts and Echelons 31 July 2019 ADP 3-90 2-5 control measures to coordinate and synchronize its operations. Assigning an AO to a subordinate headquarters decentralizes execution by empowering subordinate commanders to use their own initiative to accomplish their missions. (See ADP 6-0 for more information on AO assignment.) 2-16. Commanders normally assign AOs to subordinate maneuver units, such as brigade combat teams (BCTs) or maneuver enhancement brigades. Assigning an AO both restricts and facilitates the movement of units and use of fires. It restricts those units not assigned responsibility for an AO from moving through other AOs. It also restricts outside units from firing into an AO or allowing the effects of their fires to affect the AO. Coordination with the unit assigned the AO relieves some of these restrictions. 2-17. All units assigned an AO have the following responsibilities within the boundaries of that AO:  Terrain management.  Information collection  Civil-military operations.  Movement control.  Clearance of fires.  Security.  Personnel recovery.  Airspace control of assigned airspace.  Minimum-essential stability tasks.  Environmental considerations, if applicable. 2-18. The organizational design of the three types of BCTs and the maneuver enhancement brigade allows them to be assigned AOs. If commanders assign an AO to a unit that is not designed to perform all the tasks associated with controlling an AO, they clearly articulate which AO responsibilities they will not perform and what risk the commander is willing to assume. They also designate the units or command posts that perform those functions on their behalf. Terrain Management 2-19. Terrain management is the process of allocating terrain by establishing areas of operations, designating assembly areas, and specifying locations for units and activities to deconflict activities that might interfere with each other. Commanders assigned AOs are responsible for terrain management within the boundaries of those AOs. Throughout operations, commanders manage terrain within their boundaries by assigning subordinate units areas and positions. Their command posts track unit locations and movements and adjust control measures to deconflict space and control movements within their AOs. A higher echelon headquarters may dictate that another unit position itself within a subordinate unit’s AO. The commander assigned the AO retains approval authority for that unit’s placement. This ensures that the commander controlling the AO knows what units are in the AO and where they are located. This allows commanders to synchronize efforts. As tenants of an AO, units are required to coordinate with the headquarters assigned the AO. Information Collection 2-20. Within their AOs, commanders perform intelligence, surveillance, and reconnaissance (known as ISR) as part of their collection efforts. They perform these tasks and conduct operations to maintain current and accurate common operational pictures of their AOs. They share the common operational picture with higher echelon, adjacent, subordinate, and tenant units to maintain a clear understanding of their AOs and areas of interest. 2-21. Intelligence operations are the tasks undertaken by military intelligence units through the intelligence disciplines to obtain information to satisfy validated requirements (ADP 2-0). Intelligence operations collect information about the activities and resources of the threat or information concerning the characteristics of an operational environment. The intelligence disciplines of counterintelligence, geospatial intelligence, human intelligence, measurement and signature intelligence, signals intelligence, and technical intelligence routinely perform tasks associated with intelligence operations. (See FM 2-0 for additional information on intelligence operations.)