text: Foundations of Engineer Operations
  Engineer tasks to repair, maintain, or build roads, bridges, and airfields usually do not occur under
  conditions that require combat engineer units. As a result, these tasks are often considered general
  engineering tasks, even though combat engineer units can perform them if they are provided additional
  training and augmentation. Combat engineers can perform these tasks if performed under conditions of close
  support to maneuver forces that are in close combat.
  Engineer contributions to the planning of mobility occur at all levels of war and throughout decisive
  action. The execution of engineer tasks in support of mobility usually occurs at the operational and tactical
  levels of war, but it often has strategic-level implications. At the tactical level of war, combat engineer units
  are frequently required, especially in offensive and defensive operations. At the operational level, engineer
  tasks are typically performed by general engineer units. During the conduct of offensive and defensive
  operations, engineer tasks are focused on the mobility of friendly forces. In stability and DSCA, engineer
  tasks are often focused on the mobility of the first responders and the population.
  Engineer tasks that support mobility typically support the assure mobility line of engineer support, but
  they may also support the other three lines. Similarly, a road constructed for an LOC has the purpose of
  enabling sustainment. Likewise, a bridge might be constructed to develop infrastructure, allowing the local
  population to transport goods to the market. Engineers perform these tasks most frequently as part of the
  movement and maneuver warfighting function, but they may perform them in support of the other warfighting
  functions. Combat engineering is typically focused on mobility at the tactical level, while general engineering
  is typically focused on mobility at the operational level (although general engineering may impact strategic
  mobility at times).
  Mobility tasks are typically identified as essential tasks and may require integration into the
  synchronization matrix to account for the assets and the time required to implement them. See chapter 3 for
  a discussion of planning considerations for M/CM/S.
  Support to Countermobility
  Engineer support to countermobility includes the following engineer tasks:
  * Siting obstacles.
  * Constructing, emplacing, or detonating obstacles.
  * Marking, reporting, and recording obstacles.
  * Maintaining obstacle integration.
  Countermobility operations are those combined arms activities that use or enhance the effects of
  natural and man-made obstacles to deny enemy freedom of movement and maneuver (ATP 3-90.8). The
  primary purpose of countermobility is to slow or divert the enemy, increase the time for target acquisition,
  and increase weapon effectiveness. The advent of rapidly emplaced, remotely controlled, networked
  munitions enables engineers to conduct an effective countermobility operation as part of the offense, defense,
  or stability operation and during the transitions among these operations.
  Countermobility tasks typically involve engineers and must always include proper obstacle integration
  with the maneuver plan, adherence to the obstacle emplacement authority, and rigid obstacle control. The
  engineer advises the commander on how to integrate the obstacle, coordinates for the obstacle emplacement
  authority, establishes obstacle control, recommends directed obstacles, supervises the employment of
  obstacles, and maintains obstacle status throughout the operation. Most obstacles have the potential to deny
  the freedom of maneuver to friendly and enemy forces. Therefore, it is critical that the engineer accurately
  understands the countermobility capabilities and limitations of the available engineer forces and properly
  weighs the risks of employing various obstacle types. The engineer must also plan for the clearing of
  obstacles at the cessation of hostilities and for minimizing obstacle effects on noncombatants and the
  environment.
  The engineer tasks that support countermobility operations include those that construct, emplace, or
  detonate obstacles and those that track, repair, and protect obstacles. Combat engineer tasks are performed
  by engineers in close support to land combat forces. These conditions frequently occur when the tasks are
  conducted at the tactical level as part of the offense or defense. They are often considered combat engineering
  tasks, even though general engineer units can perform them when the conditions allow.