text: The Defense
  damage. This can also make it harder to mass effects. Units position forces and installations to avoid
  congestion, but do not disperse them to the extent that there is a risk of defeat in detail by an enemy force
  employing conventional munitions or weapons of mass destruction.
  8-115. Units also use cover to limit the amount of damage and casualties that they can receive because of
  an enemy attack. Folds in the earth, natural depressions, trees, buildings, and walls offer cover; individuals
  and units seek them out and use them habitually. If units deploy in flat terrain lacking cover, digging in or
  sandbagging can offer some protection. The unit employs obscuration if it is moving and cannot use natural
  cover or cannot build fortifications. Obscurants (including smoke) make target acquisition much more
  difficult for attacking forces. The defending unit must do everything it can to avoid an attack in the first place
  as part of its survivability measures, but if it is attacked, it uses cover and dispersion to limit the amount of
  damage.
  8-116. In addition to cover and concealment units employ tactical deception to increase their survivability.
  This can include use of decoys, frequent repositioning of units, and construction of false battle positions.
  (See Chapter 19 for more information on tactical deception.)
  Air and Missile Defense
  8-117. Army AMD units will not normally be positioned to provide AMD support to security forces in the
  defending unit’s security area. Short-range air defense units may be assigned or attached to defending units
  to support maneuver forces and protect critical static assets. They may be able to range portions of the MBA
  to provide some general support. Generally, defending ground forces depend on offensive and defensive
  counterair warfare operations conducted by fixed-wing aircraft and short- and long-range surface-to-air
  missiles for defense against enemy aircraft and missiles. Defending ground units employ small arms air
  defense against enemy aircraft attacking their positions and enemy UASs.
  8-118. Air and missile defense supports the conduct of the defense by engaging targets throughout the
  assigned area with air and missile defense fires and defensive counterair operations. In the defense, general
  fire support considerations for supporting the concept of operations include—
  * Planning for target acquisition and sensors to provide coverage of NAIs, TAIs, and critical assets.
  * Providing fires in support of defensive counterair operations to prevent enemy aerial attacks.
  * Providing integrated air and missile defense fires in synchronization with maneuver and
  electromagnetic warfare countermeasures in the conduct of decisive and shaping operations.
  * Providing fires to support counterattacks.
  * Providing fires in support of main and supporting efforts.
  See JP 3-01 for additional information on joint counterair operations.
  Force Health Protection
  8-119. Defensive operations can result in prolonged occupation of static positions and corresponding
  exposure of personnel and equipment to weather and other environmental effects or health threats that can
  quickly degrade readiness. Proper planning and employment of force health protection asset to mitigate
  potential health threats is critical to conducting defensive operations. Units enforce environmental
  disciplines, such as hydration, field hygiene and sanitation, protective clothing, and maintenance. Defensive
  operations also may entail sustained enemy bombardments resulting in dramatic effects on the mental and
  behavioral health of unit personnel. Soldiers can become combat ineffective from heavy indirect fire, even if
  exposure is for short durations. Units deliberately emplace systems for combat and operational stress
  identification and treatment to reduce the return to duty time of affected personnel.
  Chemical, Biological, Radiological, and Nuclear
  8-120. Defending units in static positions are vulnerable to CBRN threats and hazards. Units specify the
  degree of acceptable risk and establish priorities for their CBRN assets. They must balance the dispersion of
  forces and installations to increase CBRN survivability with the ability to mass overwhelming combat power
  to defeat enemy forces.