text: Security Operations
  of the protected force dictates the movement of security forces. Security force commanders normally assign
  additional lateral boundaries in their security areas to delineate assigned areas for subordinate units.
  13-55. Units use checkpoints and NAIs to coordinate and synchronize movement and collection. They use
  contact points to facilitate coordination with flank units during front and rear security missions or between
  elements of a security force in the security area. Units conducting flank security for a moving force physically
  contact their main bodies at contact points. Security force units establish observation posts or coordinate for
  aerial assets to ensure coverage of specific NAIs or avenues of approach as necessary.
  Note. For the descriptions below, the security force’s security objective is their higher
  headquarters’ main body.
  SCREEN
  13-56. Screen is a type of security operation that primarily provides early warning to the protected force
  (ADP 3-90). Screens provide less protection than guards or covers. Screen missions are defensive in nature
  and accomplished by establishing a series of observation posts and patrols to ensure observation of the
  assigned sector. The screen force gains and maintains enemy contact consistent with the fundamentals and
  destroys or repels enemy reconnaissance units by conducting counterreconnaissance. Counterreconnaissance
  is a tactical mission task that encompasses all measures taken by a unit to counter enemy reconnaissance and
  surveillance efforts. A unit performing a screen observes, identifies, and reports enemy actions. Generally, a
  screening force engages and destroys enemy reconnaissance elements within its capabilities—augmented by
  indirect fires—but otherwise fights only in self-defense. The screen has the minimum combat power
  necessary to provide early warning and allows commanders to retain the bulk of the main body’s combat
  power for commitment at the decisive place and time. A screen provides the least amount of protection of
  any security mission; it does not have the combat power to develop the situation.
  13-57. A screen is appropriate to cover gaps between forces, exposed flanks, or the rear of stationary and
  moving forces. Units can place a screen in front of a stationary formation. Designed to provide minimum
  security with minimum forces, a screen is usually an economy of force operation. Units assign and resource
  a guard or cover mission instead of a screen if they expect significant enemy forces or they require a
  significant amount of time and space to provide the required degree of protection. The security element
  forward of a moving force conducts a guard or cover because a moving screen lacks the combat power to
  defeat or contain the lead elements of an enemy force.
  13-58. A security force normally conducts a screen by establishing a series of observation posts and patrols
  to ensure adequate surveillance of the assigned area. Units use reconnaissance patrols (mounted, dismounted,
  and aerial), relocate observation posts, and employ technical assets to ensure continuous and overlapping
  surveillance. They also employ terrain data-base analytical support systems to ensure the integration of
  friendly information collection assets to provide necessary coverage.
  Screen Tasks
  13-59. Unless the commander orders otherwise, a security force conducting a screen performs these tasks
  within the limits of its capabilities:
  * Detect and report all enemy elements attempting to pass through the screen, both ground and
  aerial, and provide the protected force commander early warning of enemy activities.
  * Conduct counterreconnaissance to destroy, defeat, or disrupt all enemy reconnaissance elements
  within capabilities and according to engagement criteria. Allow no enemy ground element to pass
  through the screen undetected and unreported.
  * Maintain contact with the protected force and other forces operating on its flank.
  * Maintain contact with enemy forces and report activity in the assigned area.
  * Maintain continuous observation of all avenues of approach that affect the main body’s mission.
  * Locate and identify the lead elements that indicate the enemy’s main attack, as prescribed in the
  enemy’s order of battle based on the IPB (when facing an echeloned enemy force).