text: Defense
  7-112. BCT subordinate commanders and leaders performing reconnaissance, surveillance, and security
  missions understand that these missions often start before the commander fully develops the plan.
  Commanders and leaders have to be responsive to changes in orientation and mission. The commander
  ensures that the staff plans,prepares,and assesses the execution of the information collection portion of the
  overall plan. (See chapter 5 for a detailed discussion on reconnaissance operations.)
  Security
  7-113. The higher commander defines the depth of the BCT’s security area. The BCT’s security area
  extends from the forward edge of the battle area to the BCT’s forward boundary. Depth in the security area
  gives the forces within the MBAmore reaction time. Depth allows the security force more area to conduct
  security missions. A very shallow security area may require more forces and assets to provide the needed
  reaction time.
  7-114. The BCT commander must clearly define the objective of the security area. The commander states
  the tasks of the security force in terms of time required or expected to maintain security, expected results,
  disengagement and withdrawal criteria,and follow-on tasks. The commander identifies specific avenues of
  approach and NAI on which the security force must focus. The BCT assists in the rearward passage of lines
  and movement through the BCT area of operations of any division and corps security force deployed beyond
  the BCT’s forward boundary.
  7-115. The BCT commander balances the need for a strong security force to shape the battle with the
  resulting diversion of combat power from the decisive operation in the MBA. The BCT frequently executes
  the forward security mission as a guard or screen. Typically,there are two options for organizing the security
  force. The BCT forward defending maneuver battalions establish their own security areas or the maneuver
  battalions provide security forces that operate with the Cavalry squadron under the BCT’s direct control.
  7-116. The BCT conducts counterreconnaissance and area security operations (see chapter 8), and
  implements local security measures, operations security, and information protection activities to deny the
  enemy information about friendly dispositions. BCT reconnaissance and security forces seek to confuse the
  enemy about the location of the BCT’s main battle positions,to prevent enemy observation of preparations
  and positions, and to keep the enemy from delivering observed fire on the positions. The BCT conducts
  reconnaissance and security operations to gain and maintain contact with the enemy,develop the situation,
  answer CCIRs, retain freedom of maneuver, consolidate gains, secure the force, and protect the local
  population. (See chapter 5 for a detailed discussion on security force operations.)
  Main Battle Area
  7-117. The main battle areais the area where the commander intends to deploy the bulk of the unit’s combat
  power and conduct decisive operations to defeat an attacking enemy (ADP 3-90). The BCT’sMBAextends
  from the forward edge of the battle area to the unit’s rear boundary. The commander selects the MBAbased
  on the higher commander’s concept of operations, IPB, results of initial information collection plan
  (reconnaissance, security operations, surveillance, and intelligence operations), and the commander’s own
  assessment of the situation.
  7-118. The BCT commander delegates responsibilities within the MBA by assigning areas of operations
  and establishing boundaries to and for subordinate battalions. The commander locates subordinate unit
  boundaries along identifiable terrain features and extends them beyond the forward line of own troops by
  establishing forward boundaries. Unit boundaries should not split avenues of approach or key terrain. The
  BCT is responsible for terrain management,security,clearance of fires,and coordination of maneuver among
  other doctrinal responsibilities within the entire area of operations if the commander does not assign area of
  operations to subordinate battalions. (See ADP 3-90 for additional information.)
  Reserve
  7-119. The reserve is not a committed force. The BCT commander can assign it a wide variety of tasks on
  its commitment,and it must be prepared to perform other missions. The reserve may be committed to restore
  the defense’s integrity by blocking an enemy penetration, reinforcing fires into an EA, or conducting a