Infantry Drills

3-151: Perimeter Defense

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3-151. The platoon leader can employ the perimeter defense as an option when
conducting an area or mobile defense. A perimeter defense is a defense oriented in all directions. (See figure 3-13, page 3-44.) The Infantry platoon uses it for self-security, and to protect other units located within the perimeter. The platoon can employ a perimeter defense in urban or woodland terrain. The platoon might be called upon to execute the perimeter defense under a variety of conditions, including:

  • When it must secure itself against terrorist or insurgent attacks in an urban area.
  • This technique also may apply if the platoon must conserve or build combat power in order to execute offensive tasks or patrolling missions.
  • When it must hold critical terrain in areas where the defense is not tied in with adjacent units.
  • When it has been bypassed and isolated by the enemy and must defend in place.
  • When it conducts occupation of an independent assembly area or reserve position.
  • When it begins preparation of a strongpoint.
  • When it is directed to concentrate fires into two or more adjacent avenues of approach.
Figure 3-13. Platoon perimeter defense

Next: 3-152: Preparations

Go Back To: U.S. Army FM 3-21.8: The Infantry Rifle Platoon and Squad