text: Chapter 6
  Defensive Considerations in Counterinsurgency
  “A defensive attitude is almost always to be deprecated and only under certain
  special circumstances is it to be recommended. The operations of regular troops
  in such warfare (small wars) must never be allowed to stagnate; the troops must be
  up and doing, striking their adversaries when these attempt resistance, hunting them
  down when they shun combat.”
  COL C. E. Callwell, Small Wars, 1896
  Insurgents will not passively let counterinsurgent forces disrupt their plans
  and isolate them from the populace. They will attack counterinsurgent forces when
  they feel that they have a good chance of success. Additionally, the insurgents will
  choose targets with an eye towards reducing the legitimacy of the established
  government. The conduct of defensive operations in COIN is very much like that in a
  conventional defense. However, in COIN, the counterinsurgent must be concerned
  with securing the HN population, HN government, and infrastructure. This chapter
  will examine defensive operations, defensive operations as they apply specifically
  to establishing civil security and civil control, defensive operations as they apply to
  the other lines of effort, and security operations.
  Section I—OVERVIEW
  Tactical formations conduct three types of defensive operations in every environment—area defense, mobile
  defense, and retrograde. At the tactical level, counterinsurgency units focus mostly on executing an area
  defense, although, there may be instances where mobile defense or retrograde are appropriate.
  AREA DEFENSE
  6-1. This type of defensive operation concentrates on denying enemy forces access to designated
  terrain for a specific time rather than destroying the enemy outright (FM 3-0). In counterinsurgencies, both
  the insurgency and the counterinsurgent are vying for the support of the population as if it were terrain.
  The focus of the area defense is on retaining terrain where the bulk of the defending force positions itself
  in mutually supporting, prepared positions. In counterinsurgencies, commanders choose an area defense
  to secure the population by living among the population employing the seven COIN lines of effort.
  Examples of an area defense in counterinsurgencies are a combat outpost next to a city market, a
  permanent squad position at an electrical plant, and a checkpoint near a police station.
  MOBILE DEFENSE
  6-2. This type of defensive operation concentrates on the destruction or defeat of the enemy through a
  decisive attack by a striking force (FM 3-0). The mobile defense focuses on defeating or destroying the
  enemy by allowing him to advance to a point where he is exposed to a decisive counterattack by the
  striking force. Mobile defense operations are less common in counterinsurgencies, because insurgents
  rarely mass. However, strike operations can be useful in destroying guerrilla bases. Another example of a
  mobile defense at the tactical level is the use of quick reaction forces to exploit tactical intelligence.