text: Security Operations
  5-127. A unit establishes a perimeter when it secures an area where the defense does not have a supporting
  unit. Perimeters vary in shape and distribution of assets based upon the results of mission analysis, IPB, and
  METT-TC (I). A probable direction of attack based on the enemy’s most likely and most dangerous courses
  of action, as determined in the IPB, may require the massing of combat power in that portion of the perimeter
  to defeat an attack or infiltration. If the perimeter was inward-focused as in stability tasks, the massing of combat
  power would prevent exfiltration or a breakout from the secured area.
  5-128. Usually, the unit establishing the perimeter divides it into subordinate unit sectors with boundaries
  and contact points. The unit employs integrated observation posts, integrating attack and reconnaissance
  aviation, ground-based sensors, UASs, HUMINT assets, and mounted and dismounted patrols. Commanders
  emplace attached tanks and other antiarmor weapon systems to orient on high-speed avenues of approach.
  UASs and ground-based sensors provide overlapping reconnaissance capabilities at extended distances from
  the perimeter.
  Figure 5-16. Cavalry squadron conducting area security
  5-129. Area security is a frequent mission conducted during stability tasks when circumstances may not
  permit establishment of clearly defined perimeters. When a perimeter is not feasible, the Cavalry unit secures
  the area by establishing a presence and conducting reconnaissance tasks throughout the area. Subordinate