text: Chapter 18
  Successful suppression generally triggers the rest of the actions at the POB. Fire control measures ensure that
  all fires are synchronized with other actions at the POB. The mission of the support force is to suppress the
  enemy overwatching the obstacle. The breach force also provides additional suppressive fires as the situation
  dictates; however, it’s primary roles are first, to secure the near side objective, and then to reduce the obstacle.
  18-25. In complex or restrictive terrain, effective suppression may have to be achieved through close-in
  fighting. Defenders will tend to be more fortified when defending in urban terrain and may be more difficult
  to suppress. Forces tasked with suppressing the enemy may find it necessary to seize terrain at or on the far
  side of the obstacle to achieve their mission. Fighting to achieve enemy suppression will likely be
  decentralized, and the ability to use indirect fires will be restricted due to the proximity of friendly and enemy
  forces and civilians.
  Obscure
  18-26. Breach forces conduct breaching using available natural cover and concealment. They employ
  battlefield obscuration, which hampers enemy observation and target acquisition of the breach force as it
  reduces the obstacle and the assault force as it passes through the obstacle. Obscuration requires close
  coordination, control, and detailed planning to maximize the desired effects on the enemy while not degrading
  friendly capabilities. This is especially important when conducting breaching in complex or restrictive terrain
  due to the close-in nature of the fighting. In urban areas, indirect delivered obscuration and suppressive fires
  will be more restricted. In some situations, using mortars (because of the ability to fire high-level trajectory),
  smoke pots, and smoke grenades rather than artillery-fired obscurants may be more effective. Planners
  consider the effects of wind and the time and assets required to build and maintain effective obscuration for
  the desired duration. Using indirect fire to provide obscuration often competes with other mission
  requirements and requires priorities to be established. Obscuration employed in multiple locations and at
  various times can confuse the enemy on the specific location and timing of breaching. (See ATP 3-11.50 for
  more information on obscuration.)
  Secure
  18-27. Forces conducting a breach secure the reduction area to prevent the enemy from interfering with
  obstacle reduction and the passage of the assault force through the created lanes. The reduction area must be
  secured before attempting to reduce the obstacle. The higher headquarters breaching unit is responsible for
  isolating the breach area by fixing enemy forces in their current positions, attacking enemy reserves in-depth,
  and providing counterfire.
  18-28. Identifying the extent of the enemy defense is critical in selecting the appropriate technique to secure
  the point of breach. The point of breach is secured before reducing the obstacle.
  18-29. The breach force is resourced with sufficient maneuver assets to provide local security against the
  enemy that the support force cannot adequately engage. Elements within the breach force that secure the
  reduction area may also be used to suppress the enemy once reduction is complete. Breaching elements
  prepare their breaching assets for employment throughout the secure phase.
  Reduce
  18-30. Normally, engineers and reduction assets (mobility capabilities) are used to reduce an obstacle. The
  number and width of lanes needed depend on the enemy situation, terrain, size and composition of the assault
  force, and scheme of maneuver. The lanes must allow the assault force to pass through the obstacle rapidly.
  In complex or restrictive terrain, the assault force may be constrained to a single lane and the assault force
  commander must ensure that the sequencing of forces through the lane is appropriate to achieve the mission.
  The breach force will reduce, proof, mark, and report lane locations and the lane marking method to higher
  headquarters. Follow-on units will further reduce or clear the obstacle, as required. Reduction begins when
  effective suppression and obscuration have been established, the obstacle has been confirmed, and the
  reduction area is secure.