text: ________________________________________________________________________________Chapter 10
  10-49. ODs formed by an OSC may be assigned in a supporting relationship
  to the OSC’s subordinate maneuver units, or they can act independently at
  the OSC level (for example, to protect an exposed flank). They are a standard
  feature of tactical and operational task organizations. With their ability to
  rapidly lay mines and construct obstacles, their mission is to deny the enemy
  access to key terrain, particularly those avenues of approach most suitable
  for armored vehicles.
  10-50. Although the OD can operate independently, it usually operates with
  an ATR to provide flank protection and to repel enemy counterattacks. ATRs
  may provide covering fire over the minefields that the ODs emplace. The OD
  sometimes operates with mechanical minelaying platoons.
  Offense
  10-51. In the offense, the OD usually moves with the ATR either on an open
  flank or in a central position ready to deploy to any threatened axis. In the
  latter case, it usually advances with maneuver units to ensure a prompt re-
  sponse to any threat.
  10-52. The OPFOR considers surprise a critical factor in mine warfare.
  Enemy reconnaissance can discover minefields laid too long in advance and
  can take measures to overcome them. Therefore, it is often more effective to
  lay a minefield during the course of a battle, preferably at the last minute,
  directly in the path of a developing threat. Using mines in this way is not
  only tactically advantageous, but also economical. This may be an important
  consideration when supplies are limited.
  10-53. The OPFOR uses ODs aggressively, maintaining close contact with
  the enemy and attempting to mine areas in which the enemy has already
  committed himself. An OD may join an ATR to ward off enemy counterattack
  threats.
  Defense
  10-54. In the defense, the OPFOR commander may hold the OD and other
  forces in reserve and can quickly employ them during an enemy attack, to
  mine potentially vulnerable gaps. Engineer tasks during the defense imple-
  ment obstacle plans, particularly AT obstacles. Together with ATRs, ODs
  provide a quick-reaction AT force to block enemy penetrations.
  10-55. Engineers create obstacles on possible enemy approaches to OPFOR
  battle positions or artillery and air defense firing positions, in the gaps
  between battle positions, and on flanks. They normally construct barrier
  systems in coordination with the overall fire support plan.
  10-56. Engineers can lay mines and construct obstacles in the disruption
  zone and on likely enemy armored avenues of approach. They can also lay
  obstacles in the depth of friendly units in the battle zone, and at subsequent
  defensive lines throughout the AOR. However, simultaneous obstacle
  construction throughout the AOR can only occur when sufficient time, equip-
  ment, and personnel are available. In any part of the AOR, minefields and
  other obstacles require barriers, security, and marked maneuver passages.