text: Appendix C
  Figure C-1. Inner and outer arms of an encirclement
  C-5. The encirclement unit organizes only an encircling arm if there is no possibility of the encircled forces
  receiving relief from enemy forces outside the encirclement. If there is danger of an enemy relief force
  reaching the encircled enemy force, the unit organizes both an inner and outer encircling arms. The
  commander assigns the outer encircling arm a security mission, an offensive mission to drive away any
  enemy relief force, or a defensive mission to prevent the enemy relief force from making contact with the
  encircled enemy force. Once the encirclement is complete, these inner or outer encircling arms form a
  perimeter.
  C-6. The second phase of an encirclement operation involves actions taken against an isolated enemy force.
  The commander’s decision to fix, contain, or destroy isolated enemy forces affects the task organization of
  subordinate units, as do enemy attempts to break out from the encirclement or linkup with the encircled force.
  All these possible outcomes require resources in terms of units and supplies, but some require more resources
  than others do. If the unit’s mission is to contain or fix an isolated enemy force, the unit organizes subordinate
  forces for defensive action and arranges them around the enemy force’s perimeter. If the unit’s mission is to
  reduce or destroy that same enemy force, that unit organizes subordinate forces for offensive action. A higher
  echelon commander often assigns either mission to the commander of a follow and support force.
  C-7. Regardless of whether a commander decides to fix, contain, or destroy enemy forces, the unit conducts
  reconnaissance to maintain contact and monitor enemy force actions in response to the encirclement. This
  allows the unit to respond effectively to any enemy movement. The most effective reconnaissance combines
  ground, aerial, and surveillance systems to provide constant coverage and multiple assessments of enemy
  activities throughout the encircled area.
  ENCIRCLEMENT CONTROL MEASURES
  C-8. As shown in figure C-2, control measures for an encirclement are similar to those of other offensive
  operations, especially an envelopment, but with a few additional considerations. If the encirclement unit uses
  both an inner and an outer encircling arm, the unit must establish a boundary between them. The unit places
  the boundary so that each element has enough space to accomplish their mission. The inner force requires
  enough space to fight a defensive battle to prevent the encircled force from breaking out. The outer force
  requires adequate terrain and depth in its assigned area to defeat any attempt to relieve the encircled force.