text: The Brigade Combat Team and the Operational Environment
  Desert Terrain
  2-19. Operations in desert terrain require adaptation to the terrain and climate. Equipment must be adapted
  to a dusty and rugged landscape with extremes in temperature and changes in visibility. The BCT orients on
  primary enemy approaches but prepares for an attack from any direction. Considerations for operations in
  desert terrain include lack of concealment and the criticality of mobility;use of obstacles to site a defense,
  which are limited;strong points to defend choke points and other key terrain;and mobility and sustainment.
  (SeeFM 90-3 for additional information.)
  Jungle Terrain
  2-20. Operations in jungle terrain combine dispersion and concentration. For example,a force may move out
  in a dispersed formation to find the enemy. Once the force makes contact,its subordinate forces closeinon
  the enemy from all directions. Operations are enemy-oriented,not terrain-oriented. Forces should destroy the
  enemy wherever found. If the force allows the enemy toescape,the force will have to find the enemy again,
  with all the risks involved. Jungle operations use the same defensive fundamentals as other defensive
  operations. Considerations for offensive and defensive operations in a jungle environment include limited
  visibility and fields of fire,ability to control units,and limited and restricted maneuver. (SeeATP 3-90.98
  for additional information.)
  Subsurface Areas
  2-21. A subsurface area is a condition found in all four operational environments described in paragraphs
  2-16 through 2-20. Subsurface areas are below the surface level (ground level) that may consist of
  underground facilities, passages,subway lines,utility corridors or tunnels, sewers and storm drains, caves,
  or other subterranean spaces. This dimension includes areas both below the ground and below water.
  Additional subterranean areas include drainage systems, cellars, civil defense shelters, mines, military
  facilities, and other various underground utility systems. In older cities, subsurface areas can include
  pre-industrial age hand-dug tunnels and catacombs. (See ATP3-21.51 for information on threat and
  hazardous subterranean structures existing or operating in concealment or hidden or when utilized in secret
  by an enemy or adversary.)
  2-22. Subsurface areas may serve as secondary and,in fewer instances,primary avenues of approach at lower
  tactical levels. Subsurface areas are used for cover and concealment,troop movement,command functions,
  and engagements,but their use requires intimate knowledge of the area. When thoroughly reconnoitered and
  controlled, subsurface areas offer excellent covered and concealed lines of communications for moving
  supplies and evacuating casualties. Attackers and defenders can use subsurface areas to gain surprise and
  maneuver against the rear and flanks of an enemy and to conduct ambushes. However,these areas are often
  the most restrictive and easiest to defend or block. The commander may need to consider potential avenues
  of approach afforded by the subsurface areas of rivers and major bodies of water that border urban areas.
  2-23. Knowledge of the nature and location of subsurface areas is of great value to both friendly and enemy
  forces. The effectiveness of subsurface areas depends on superior knowledge of their existence and overall
  design. A thorough understanding of the environment is required to exploit the advantages of subsurface
  areas. Maximizing the use of these areas could prove to be a decisive factor while conducting offensive and
  defensive operations, and stability operations tasks. (See ATTP 3-06.11, TC 2-91.4, ATP 3-06, and
  ATP3-34.81for additional information on subsurface areas.)
  SECTION II – UNDERSTAND, SHAPE, AND INFLUENCE
  2-24. The BCT commander must understand the operational objectives and tactical situation, cultural
  conditions, and ethical challenges of the operational environment, in order to shape the operational
  environment through action,influence the population and its leaders,and consolidate gains(see section III)
  to seize, retain, and exploit disciplined initiative throughout the range of military operations (see
  paragraph2-3). Regardless of which element of decisive action (offense, defense, or stability) currently
  dominates (see paragraph 2-73),the commander conducts multiple missions assessing and balancing the need
  for decisive action, judicious restraint, security, and protection to shape the operational environment and
  seeks to achieve a common goal and end state that nests with higher command objectives. The BCT