Section 2 – Common Defensive Planning Considerations

5-29. Planning a defensive operation is a complex effort requiring detailed planning and extensive coordination. In the defense, synchronizing the effects of the Infantry rifle platoon’s capabilities enables the platoon leader to apply overwhelming combat power against selected advancing enemy forces to disrupt the enemy’s plan. As an operation evolves, the platoon leader knows a shift to main and supporting efforts is a probability to press the fight and keep the enemy off balance. Warfighting functions provide the Infantry leader a means and structure for planning, preparing, executing, and assessing the defense. The following paragraphs discuss the synchronization and coordination of activities within each warfighting function critical to the success of the Infantry rifle platoon and squad. Additionally, this section addresses environmental planning considerations in the defense. (See FM 3-96 for additional information.)

Command And Control

5-30. The first step is the expression of the platoon leader’s vision of anticipated enemy actions integrated with the Infantry rifle company’s intelligence preparation of the operational environment (known as IPOE). The Infantry battalion and company IPOE should not differ significantly, giving the Infantry platoon and squad a clear understanding of how the Infantry battalion and company commanders envision the enemy fight and plan for the operation. The company commander refines the IPOE to focus on the details of the operation in the company AO. The platoon leader refines the IPOE to focus on the details of the mission in the platoon AO. The Infantry battalion commander usually defines where and how the Infantry battalion will defeat or destroy the enemy. The Infantry rifle company commander and platoon leader then describe a vision of how their units will execute their portion of the battalion fight.

5-31. The platoon’s leaders will locate where they can best provide command and control to subordinate units and Soldiers. Understanding the enemy’s likely scheme of maneuver allows the platoon leader to select those decisive point(s) where best to position leaders and key weapons in order to mass their effects on enemy forces. When a platoon command post is established within the defense, it is located where the platoon leader determines it is best able to provide communications with higher, lower, adjacent, and supporting units; to assist the platoon leader in planning, coordinating, and issuing platoon orders, and to support continuous operations by the platoon. In static positions (for example, a battle position[s]), a stationary command post location may be designated by the platoon leader where field expedient antennas and/or land wire are employed to allow communications to be established with company, and subordinate static units, observation posts, and/or patrols within the platoon’s AO. Accurate primary, alternate, contingency, and emergency (known as PACE) communications plan (see paragraph 5-104) is crucial to a leader’s situational awareness. The PACE plan designates the order in which a leader will move through available communications systems until contact can be established with the desired element.

Movement And Maneuver

5-32. Movement and maneuver considerations involve the movement and employment of direct fire weapons on the battlefield. In the defense, weapons positioning is critical to the Infantry platoon’s and squads’ success. Weapons positioning enables the platoon to mass fires at critical points on the battlefield and shift fires as necessary. The platoon leader exploits the strengths of the weapon systems while minimizing the platoon’s exposure to enemy observation and fires.

Depth And Dispersion

5-33. Dispersing positions laterally and in-depth helps to protect the force from enemy observation and fires. The positions are established in-depth, allowing sufficient maneuver space within each position to establish in-depth placement of weapon systems and Infantry elements. Engagement areas are established to provide for the massing of fires at critical points on the battlefield. Sectors of fire are established to distribute and shift fires throughout the extent of the engagement area. Once the direct fire plan is determined, fighting positions are constructed in a manner to support the fire support and obstacle plan.

Flank Positions

5-34. Flank positions enable a defending force to fire on an attacking force moving parallel to the defender’s forces. A flank position provides the defender with a larger and more vulnerable target while leaving the attacker unsure of the defense’s location. Major considerations for employment of a flank position are the defender’s ability to secure the flank and the ability to achieve surprise by remaining undetected.

Disengagement Criteria

5-35. Disengagement criteria are the protocols that specify those circumstances where a friendly force must break contact with the direct fire and observed indirect fire to avoid becoming decisively engaged or to preserve friendly combat power (FM 3-90). It dictates to subordinate elements the circumstances, in which they will displace to alternate, supplementary, or subsequent positions. The criteria are tied to an enemy action, such as an enemy unit advancing past a certain phase line. They also are linked to the friendly situation. For example, the criteria might depend on whether artillery or an overwatch element can engage the enemy. Disengagement criteria are developed for each specific situation.

Displacement Criteria

5-36. Displacement criteria define triggers for planned withdrawals, passage of lines, or reconnaissance handovers (battle handover for security operations) between units. As with engagement, disengagement, and bypass criteria, the conditions and parameters set in displacement criteria integrate the leader’s intent with tactical feasibility. Conditions and parameters are event-driven, time-driven, or enemy-driven. Displacement criteria conditions and parameters are key rehearsal events due to the criticality of identifying the triggers to anticipate during the mission. An example of event-driven conditions and parameters are associated priority intelligence requirements (PIRs) being met, enemy contact not expected in the area, and observed named area of interest (NAI) or avenue of approach denied to the enemy. Time-driven conditions and parameters ensure the time triggers are met (for example, latest time information is of value). An observation post compromised by threat or local civilian contact is a threat-driven condition. Failure to dictate conditions and parameters of displacement, nested within the higher scheme of maneuver, results in mission failure.

Disengagement And Displacement Planning

5-37. Disengagement and displacement allow the platoon to retain its flexibility and tactical agility in the defense. For example, retrogrades (see section IV) are conducted to improve a tactical situation or preventing a worse situation from developing. Platoons usually conduct retrogrades as part of a larger force but may conduct independent retrogrades (withdrawal) as required during defensive operations. The ultimate goals of disengagement and displacement are to enable the platoon to avoid being fixed or decisively engaged by the enemy. The overarching factor in a displacement is to maintain a mobility advantage over the enemy. The platoon leader must consider several important factors in displacement planning. These factors include, among others:

  • The enemy situation, for example, an enemy attack with one company-size enemy unit might prevent the platoon from disengaging.
  • Disengagement criteria (see paragraph 5-35).
  • Availability of direct fire suppression that can support disengagement by suppressing or disrupting the enemy.
  • Availability of cover and concealment, indirect fires, and obscurants to assist disengagement.
  • Obstacle integration, including situational obstacles.
  • Positioning of forces on terrain that provides an advantage to the disengaging elements such as linear obstacles.
  • Identification of displacement routes and times when disengagement or displacement will take place. Routes and times are rehearsed.
  • The size of the friendly force that must be available to engage the enemy in support of the displacing unit.

5-38. While disengagement and displacement are valuable tactical tools, they can be extremely difficult to execute in the face of a rapidly moving enemy force. The platoon leader must establish clear disengagement criteria, and it must be rehearsed. In execution, leaders carefully evaluate the situation and are alert to those criteria. The platoon leader makes a displacement decision early enough to ensure that it is feasible and does not result in unacceptable personnel or equipment losses.

5-39. For example, in a delay from alternate positions, First Platoon in an area defense occupies delaying positions in-depth. As First Squad engages the enemy vicinity Phase Line Dog, Second Squad occupies its next position in-depth adjacent to Third Squad and prepares to assume responsibility for the operation. When the enemy reaches Phase Line Cat, First Squad disengages and passes around (preferred method) or through Second Squad. First Squad then moves to its next position and prepares to reengage the enemy while Second Squad and Third Squad take up the fight.

Direct Fire Suppression

5-40. The attacking enemy force must not be allowed to bring direct and indirect fires to bear on a disengaging friendly force. Direct fires from the base-of-fire element, employed to suppress or disrupt the enemy, are the most effective way to facilitate disengagement. The platoon may receive base of direct fire support from another element in the company, but in most cases, the platoon establishes its own base-of-fire element. Having an internal base of fire requires the platoon leader to sequence the displacement of forces.

Cover And Concealment

5-41. The platoon and subordinate squads use covered and concealed routes when moving to alternate, supplementary, or subsequent positions. Regardless of the degree of protection the route itself affords, the platoon and squads should rehearse the movement both day and night prior to contact. Rehearsals increase the speed at which they can conduct the move and provide an added measure of security. The platoon leader allocates available time to rehearse movement in limited visibility and degraded conditions.

Indirect Fires And Obscurants

5-42. Artillery or mortar fires assist the platoon during disengagement. Suppressive fires slow the enemy and cause the enemy to seek cover. Smoke obscures the enemy’s vision, slows the progress, or screens the defender’s movement out of the battle position or along the displacement route.

Obstacle Integration

5-43. Obstacle efforts create opportunities to engage enemy forces with direct and indirect fires. Leaders should plan to mass fires on the places that obstacles will force enemy forces to go, not on the obstacles themselves. Ideally, obstacles should be positioned far enough away from the defender that enemy elements could be engaged on the far side of the obstacle while keeping the defender out of range of the enemy’s massed direct fires. One or two well-constructed obstacles are more valuable than more obstacles constructed to marginal standards.

Countermobility

5-44. Countermobility is a set of combined arms activities that use or enhance the effects of natural and man-made obstacles to prevent the enemy freedom of movement and maneuver (ATP 3-90.8). To succeed in the defense, defenders reinforce the terrain to prevent the enemy from gaining a position of advantage. Reinforcing the terrain focuses on existing and reinforcing obstacles. These categories of obstacles provide a way for viewing the obstacle classification described in paragraphs 5-45 to 5-64 from the countermobility perspective. (See ATP 3-21.10 for additional information on countermobility operations in the defense.)

Existing Obstacles

5-45. Existing obstacles are inherent aspects of the terrain that impede movement and maneuver. Existing obstacles may be natural (rivers, mountains, wooded areas) or man-made (enemy explosive and nonexplosive obstacles and structures, including bridges, canals, railroads, and their associated embankments). Although not specifically designed or intended as an obstacle, structures may pose as an obstacle based on existing characteristics or altered characteristics that result from combat operations or a catastrophic event. Structures, such as bridges and overpasses, present an inherent impediment to the enemy’s mobility based on weight and clearance restrictions. Existing obstacles are shown on the combined obstacle overlay developed as part of the IPOE. As described in ATP 3-34.80, geospatial engineering is critical in accurately predicting the effects that existing obstacles will have on enemy and friendly movement and maneuver.

Reinforcing Obstacles

5-46. Reinforcing obstacles are those man-made obstacles that strengthen existing terrain to achieve a desired effect. For U.S. forces, reinforcing obstacles on land consist of land mines, networked munitions, and demolition and constructed obstacles. The basic employment principles for reinforcing obstacles are—

  • Support the maneuver commander’s plan.
  • Integrate with observation and fires.
  • Integrate with other obstacles.
  • Employ in-depth.
  • Employ for surprise.

5-47. Land mines. A land mine is a munition on or near the ground or other surface area that is designed to explode by the presence, proximity, or contact of a person or vehicle. Land mines can be employed in quantities within a specific area to form a minefield, or they can be used individually to reinforce nonexplosive obstacles. Land mines can be further qualified as antivehicle or antipersonnel. They can be air-, artillery-, or ground-delivered. Land mines fall into two general categories:

  • Persistent. A persistent mine is a land mine, other than nuclear or chemical, that is not designed to self-destruct. It is designed to be emplaced by hand or mechanical means and can be buried or surface emplaced.
  • Nonpersistent. A nonpersistent mine remains active for a predetermined period of time until self-destruction, self-neutralization, or self-deactivation renders the mine inactive. This means that it is capable of self-destructing or self-deactivating.

Note. As of 31 January 2020, U.S. forces are not authorized to employ persistent or nondetectable land mines.

5-48. Networked munitions. Networked munitions are remotely controlled, interconnected, weapon systems designed to provide rapidly emplaced ground-based countermobility and protection capability through scalable application of lethal and nonlethal means (JP 3-15).

5-49. Demolition obstacles. Demolition obstacles are created using explosives. Examples include bridge or other structure demolition (rubble) and road craters. (See ATP 3-90.8 appendix B for additional information on demolition obstacles.)

5-50. Constructed obstacles. Constructed obstacles are created without the direct use of explosives. Examples include wire obstacles, antivehicle ditches, or similar construction that involves the use of heavy equipment.

5-51. Reinforcing obstacles are categorized as tactical and protective. They are employed as part of the movement and maneuver and protection warfighting functions. (See ATP 3-90.8 for additional information.) In the defense, leaders use reinforcing obstacles to:

  • Slow the enemy’s advance to give the platoon or squad more time to mass fires on the enemy.
  • Protect defending units.
  • Canalize the enemy into places where they can easily be engaged.
  • Separate the enemy’s armor from its infantry.
  • Strengthen areas that are lightly defended.
Tactical Obstacles

5-52. The primary purposes of tactical obstacles are to shape enemy maneuver and to maximize the effects of fires. Tactical obstacles directly attack the ability of a force to move, mass, and reinforce; therefore, they affect the tempo of operations. Leaders integrate obstacles into the scheme of movement and maneuver/scheme of maneuver to enhance the effects of fires. Preexisting obstacles that a unit reinforces and integrates with observation and fires may become tactical obstacles. The types of tactical obstacles are clearly distinguished by the differences in execution criteria. The three types are—directed obstacles, situational obstacles, and reserved obstacles.

5-53. A directed obstacle is an obstacle directed by a higher commander as a specified task to a subordinate unit (ATP 3-90.8). The higher commander directs and resources these obstacles as specified tasks to a subordinate unit. Unit leaders plan, prepare, and execute directed obstacles during the preparation of the AO. Most tactical obstacles are directed obstacles.

5-54. A situational obstacle is an obstacle that a unit plans and possibly prepares prior to starting an operation but does not execute unless specific criteria are met (ATP 3-90.8). They are preplanned obstacles as part of a target area of interest and provide the commander flexibility for emplacing tactical obstacles based on battlefield development. Situational obstacles can incorporate any type of obstacle that can be employed within the time required. Situational obstacles are used to get inside the decision cycle of the enemy or react promptly to unexpected situations. Situational obstacles help units retain flexibility to quickly adapt in changing environments. Situational obstacles support the maneuver commander’s synchronization matrix, decision support template, or branches and sequels. The following should be considered in addition to the obstacle employment principles:

  • Identifying the need for a situational obstacle.
  • Planning for the appropriate resources.
  • Planning for the obstacle.
  • Identifying obstacle execution triggers.
  • Withholding the execution of the obstacle until needed.

Note. The U.S. ban on persistent land mines has resulted in a greater reliance on scatterable mines to fulfill tactical obstacle requirements. The limited duration of scatterable mines (after their activation) makes them the most suitable for use as situational obstacles.

5-55. A reserved obstacle are obstacles of any type, for which the commander restricts execution authority (ATP 3-90.8). The commander specifies the unit that is responsible for preparing, guarding, and executing reserved-obstacle emplacement. Units execute them only on command of the designating commander or based on specific criteria identified by the commander. The purpose of a reserved obstacle is to retain control over the mobility along an avenue of approach. Commanders use reserved obstacles when failure to maintain control over the mobility along an avenue of approach will have disastrous effects on the current battle or future operations.

Note. The three definitions above can apply to any type of obstacle. For example, the Modular Pack Mine System can be employed in support of disengagement, to either block a key displacement route once the displacing unit has passed through it or close a lane through a tactical obstacle. The location of obstacles in support of disengagement depends on mission variables of METT-TC (I) mission, enemy, terrain and weather, troops and support available, time available, civil considerations, and informational considerations.

Protective Obstacles

5-56. Protective obstacles have two roles: defense or security. Infantry platoons plan and construct their own protective obstacles. For best effect, protective obstacles are tied into existing or tactical reinforcing obstacles. The platoon can use mines and wire, or it might receive additional materiel from the company, for example, Classes IV or V. In planning protective obstacles:

  • The platoon leader evaluates the potential threat to the platoon’s position. Then, employs the best system for that threat.
  • Protective obstacles usually are located beyond hand grenade distance (40 to 100 meters) from the Soldier’s fighting position and may extend out 300 to 500 meters to tie into tactical obstacles and existing restricted terrain. (As with tactical obstacles, the platoon leader should plan protective obstacles in depth and try to maximize the range of the platoon’s weapons.)
  • The platoon leader considers preparation time, the burden on the logistical system, the Soldiers’ loads, and the risk of loss of surprise.

5-57. The three types of wire obstacles (see figure 5-3 on page 5-16) are protective, tactical, and supplementary:

  • Protective wire can be a complex obstacle providing all-around protection of a platoon perimeter. It also might be a simple wire obstacle on the likely dismounted avenue of approach into a squad ambush position. Command detonated M18 claymores (see TC 3-22.23) can be integrated into the protective wire or used separately.
  • Tactical wire is positioned to increase the effectiveness of the platoon’s fires. Usually, it is positioned along the friendly side of the medium machine gun final protective line (FPL). Tactical minefields also may be integrated into these wire obstacles or used separately.
  • Supplementary wire obstacles can break up the line of tactical wire. This helps prevent the enemy from locating friendly weapons (particularly the medium machine guns) by following the tactical wire.

Figure 5-3. Wire obstacles

Note. See ATP 3-90.8 for information on nuisance and phony obstacles. Nuisance obstacles impose caution on opposing forces. They disrupt, delay, and sometimes weaken or destroy follow-on echelons. Phony obstacles deceive the attacking force concerning the exact location of real obstacles. They cause the attacker to question its decision to breach and may cause the attacker to expend reduction assets wastefully.

5-58. Certain actions must occur when a protective obstacle (same actions apply for a tactical obstacle) is turned over or transferred to ensure that obstacle effectiveness or integration is not degraded. After an obstacle is completed, the emplacing unit (for example, the platoon) conducts obstacle transfer with the owning unit (for example, the company). The details for obstacle transfer (including who, what, when, and where) are established between the emplacing and owning units during obstacle siting. The owning unit may subsequently transfer ownership of an obstacle to another unit as part of a relief or unit rotation. (A withdrawal may involve obstacle removal.) Obstacle transfer ensures that the commander who is gaining ownership of the obstacle is familiar with the obstacle characteristics and features and that the responsibilities for maintaining obstacle integration are understood. In addition to the information presented in obstacle records, demolition target folders, and transfer reports (if applicable), leaders who conduct obstacle transfer should consider providing the following information to the gaining unit leader:

  • Features or characteristics of the obstacle, such as the—
    • Obstacle data, including obstacle number, grid location, and emplacement date and time.
    • Dimensions and composition.
    • Anchor points.
    • Lane-marking data.
    • Intended effect.
    • Strengths and weaknesses.
  • Updates on friendly and enemy activities near the obstacle.
  • Areas for enemy observation and likely points of breach.
  • Fire control measures.
  • Detailed instructions, along with demonstrations as necessary, for—
    • Closing lanes and gaps.
    • Repairing and maintaining obstacles.
    • Removing, clearing, dismantling, disabling, or disarming obstacles.
    • Reusing or properly disposing of recovered obstacle material.

Note. Tracking obstacle removal and obstacles remaining on the battlefield is just as critical as tracking obstacle emplacement. (See ATP 3-90.8 for additional information.)

Obstacle Intent

5-59. Obstacle intent includes the target and desired effect (clear task and purpose) and the relative location of the obstacle group. The purpose influences many aspects of the operation, from selecting and designing obstacle sites to conducting the defense. Normally, the company commander designates the purpose of an obstacle group. When employing obstacles, the platoon leader considers the following principles:

  • Support the tactical plan. Ensures obstacles supplement combat power to decrease the mobility of the enemy and provide security for the platoon. While considering enemy avenues of approach, the platoon leader also considers the platoon’s own movement requirements, such as routes for resupply, withdrawal, counterattacks, patrols, and observation posts.
  • Tie in. Ensures reinforcing obstacles are tied in with existing or natural obstacles. Ensures fire support plan supports obstacle plan, based on estimated enemy’s rate of movement and formation, amount of time it will take the enemy to breach or bypass specific obstacles, and how long it will take to process and fire each target. This allows for the creation of effective triggers that quickly synchronize fires and achieve the desired effects against enemy formations.
  • Covered by observation and fire. Ensures that all obstacles are covered by observation and fire. This reduces the enemy’s ability to remove or breach the obstacles out of contact.
  • Constructed in-depth. Emplaces obstacles so that each new obstacle encountered by the enemy attrits the enemy force or equipment and causes a desired and controlled reaction. Proper use of obstacles in-depth wears the enemy down and significantly increases the overall effect.
  • Employed for surprise. Avoids an obvious pattern of obstacles that would divulge locations of units and weapons. The platoon leader must avoid readily discernable, repetitive obstacle patterns.

5-60. The company commander assigns obstacle groups and tells the platoon leader and supporting engineers the intent of the obstacles against the enemy, and then resources the groups accordingly. Obstacle intent includes the elements of target, effect, and relative location:

  • Target identifies the targeted enemy force size, type, echelon, avenues of approach, or any combination of these.
  • Effect describes how to affect the enemy’s maneuver with obstacles and fires. Tactical obstacles block, turn, fix, or disrupt. Obstacle effect integrates the obstacles with direct and indirect fires.
  • Relative location is the placement of the obstacle effect to occur against the targeted enemy force. Initiates an obstacle integration process after identifying where on the terrain the obstacle will most decisively affect the enemy.

5-61. For example, the battalion commander might say, “deny the enemy access to the battalion’s flank by turning the northern, enemy mechanized Infantry company into Engagement Area Crow to allow A Company (specifically First Platoon and Second Platoon) to mass their fires to destroy the enemy.” Scatterable mine systems and submunitions are the main means of constructing tactical obstacles. These systems, with their self- and command-destruct capabilities, are flexible, and they aid in rapid transitions between defensive and offensive operations. They do this better than other constructed obstacles. The force constructs conventional minefields and obstacles only for a deliberate, long-term defense. In those cases, the company and platoons usually are augmented with assets from the brigade engineer battalion of the Infantry brigade combat team (IBCT) and/or a divisional engineer battalion. Table 5-1 shows the symbols for each obstacle effect, and it describes the purpose and characteristics of each.

Table 5-1. Tactical obstacle effects

Obstacle Lanes

5-62. Leaders identify mobility requirements to determine the need for lanes or gaps to be left in obstacles. Mission variables of METT-TC (I) are considered to determine if these areas remain open, closed on order, or closed with the defender able to open the lane. The on-off-on feature of networked munitions makes them well suited for lanes. Units use lanes or gaps to allow patrols (combat and reconnaissance), quick reaction forces—commander designated forces to respond to threat attacks or emergencies (FM 3-90), quick response forces, or tactical combat forces, and counterattack forces to enter and leave through the defense.

Note. A quick response force is a dedicated force on a base with adequate tactical mobility and fire support designated to defeat Level I and Level II threats and shape Level III threats until they can be defeated by a tactical combat force or other available response forces (see FM 3-90).

5-63. Lanes and gaps are weak points in protective obstacles, so units consider allocating increased direct and indirect fires to cover them. The lanes and gaps must be disseminated to all levels and overwatched as a protective measure to prevent fratricide. Obstacles that are used for rapid lane closure are often demolition obstacles or mines, for example, units may use a cratering charge to close a lane.

5-64. When the platoon is responsible for actions related to lanes through obstacles. Its duties can include marking lanes in an obstacle, reporting locations of the start and ends of each lane, operating contact points, providing guides for elements passing through the obstacle, and planning and rehearsing lane closure. (See ATP 3-90.8 for additional information.)

Mobility

5-65. Mobility operations in the defense ensure the ability to reposition forces, delay, and counterattack. Initially during defensive preparations, mobility operations focus on the ability to resupply, reposition, and conduct rearward and forward passage of forces, materiel, and equipment. Once major defensive preparations are complete, the focus normally shifts to supporting the local reserve and counterattack(s), and the higher headquarters counterattack or reserve. Priorities set by the company may specify routes for improvement in support of such missions. Normally, most engineer assets go to survivability and countermobility. At a set time or trigger, engineers disengage from obstacle and survivability position construction and start preparing for focused mobility missions. The defender analyzes the scheme of maneuver, obstacle plan, fire support plan, and terrain to determine mobility requirements. (See ATP 3-21.10 for additional information on mobility operations in the defense.) Critical considerations may include:

  • Lanes and gaps in the obstacle plan.
  • Lane closure plan and subunit responsibility.
  • Route reconnaissance, improvement, and maintenance.

Sector

5-66. A sector is an operational area assigned to a unit in the defense that has rear and lateral boundaries and interlocking fires (FM 3-0). The non-bounded side is open towards the enemy. A higher echelon headquarters uses fire support coordination and maneuver control measures such as battle positions and trigger lines to synchronize subordinate units. Higher headquarters are responsible for synchronizing operations forward of the main battle and security areas or coordinated fire line. Units use sectors to synchronize and coordinate engagement areas and allow for mutually supporting fields of fire, which do not require coordination between adjacent units. Units treat everything behind the FLOT as an AO. Sectors can be further subdivided as needed. (See FM 3-90 for additional information on sectors.)

Reserve Role

5-67. If the platoon, or squad are designated in a reserve role, positioning the reserve in a location where it can react to several contingency plans is vital to success. The designating commander considers terrain, trafficability of roads, potential engagement area(s), and probable points of enemy penetrations and commitment time when positioning the reserve. Additionally, reserve forces must understand that they may be a primary target for enemy destruction through fires or CBRN attacks and must be prepared to react to this targeting. The reserve force must understand, plan for, and rehearse multiple assigned planning priorities, and must time, and provide those times to the designating commander, for all anticipated movements.

5-68. The battalion commander can have a single reserve, or if the terrain dictates, the subordinate commanders can designate their own reserve (generally a squad or platoon). Commanders must ensure reserves are positioned in a covered and concealed position and that they cannot be trapped in these reserve positions by the enemy’s scatterable mines. Information concerning reserves may be considered essential element of friendly information and protected from enemy reconnaissance. The commander or platoon leader (when the platoon designates a reserve) might choose to position the reserve forward initially to deceive the enemy, or to move the reserve occasionally to prevent it from being targeted by enemy indirect fires.

Intelligence

5-69. The Infantry platoon leader never has all the information needed about the enemy. Therefore, the platoon leader obtains or develops the best possible IPOE products, conducts continuous reconnaissance, and integrates new and updated intelligence products and assessments and combat information throughout the operation. The leader requests information through the company from the battalion staff to answer platoon information requirements. (See ATP 3-21.10 for additional information.)

5-70. As with all tactical planning, IPOE is a critical part of defensive planning. It helps the platoon leader define where to concentrate combat power, where to accept risk, and where to plan potential decisive points in the operation. To aid in the development of a flexible defensive plan, the IPOE must present all feasible enemy courses of action (COAs). The essential areas of focus are—

  • Analyze terrain and weather.
  • Determine enemy force size and likely COAs with associated decision points.
  • Determine enemy vulnerabilities and high-value targets (generally developed during step 4 of the battalion’s IPOE, see chapter 2).
  • Impact of civilian population on the defense.

5-71. The platoon leader, in coordination with the commander, base determinations of how and where to defeat the enemy on potential future enemy locations, the terrain, and forces available. The company may define a defeat mechanism (destroy, dislocate, disintegrate, and isolate, see ATP 3-21.10) including the use of single or multiple counterattacks to achieve success. The platoon leader analyzes the platoon’s role in the company fight and determines how to achieve success.

Fires

5-72. The Infantry platoon leader plans and executes fires in a manner, which achieves the intended task and purpose of each target. The platoon’s scheme of fires serves to:

  • Slow and disrupt enemy movement.
  • Prevent the enemy from executing breaching operations.
  • Destroy or delay enemy forces at obstacles using massed or precision fires.
  • Suppress enemy support by fire elements.
  • Defeat attacks along avenues of approach with final protective fires (FPFs).
  • Disrupt the enemy to enable friendly forces to displace or counterattack.
  • Obscure enemy observation or screen friendly movement during disengagement and counterattacks.
  • Provide obscurants to separate enemy echelons or to silhouette enemy formations to facilitate direct fire engagement.
  • Provide illumination, as necessary.
  • Execute suppression of enemy air defense missions to support aviation operations.

5-73. In developing the fire plan, the platoon leader evaluates the indirect fire systems available to provide support. Considerations when developing the plan include tactical capabilities, weapons ranges, and available munitions. These factors help the platoon leader and forward observer (FO) determine the best method for achieving the task and purpose for each target in the fire plan. The Infantry rifle company fire support Soldiers contribute significantly to the platoon fight. Positioning is critical. The platoon leader, in coordination with the company fire support officer, selects positions providing the platoon FO with unobstructed observation of the AO, ensuring survivability.

Sustainment

5-74. In addition to the sustainment functions (see chapter 8) required for all missions, the platoon leader’s planning process includes pre-positioning of ammunition caches, identifying the positioning of company trains, and Classes IV and V supply points, and explosive mine supply points.

5-75. The platoon leader’s mission analysis may reveal the platoon’s ammunition requirements during an upcoming mission exceed its basic load. This requires the platoon to coordinate with the company to pre-position ammunition caches. The platoon usually positions ammunition caches at alternate or subsequent positions. The platoon also may dig in these caches and guard them to prevent their capture or destruction.

5-76. The Infantry company trains usually operate 500 to 1,000 meters or one terrain feature to the rear of the company in covered and concealed positions close enough to the platoons to provide responsive support (support distance) but out of enemy direct fire. The company trains conduct evacuation (of those wounded in action, weapons, and equipment) and resupply as required. The company first sergeant or executive officer positions the trains and supervises sustainment operations with the platoon. It is the Infantry company commander’s, along with the first sergeant’s, responsibility to ensure all subordinate units know the locations of battalion combat and field trains as well as the company casualty collection point (CCP), battalion aid station, and casualty evacuation (CASEVAC) and medical evacuation (MEDEVAC) procedures. The platoon leader’s analysis determines the measures for every mission. The platoon sergeant responses to whatever system of supply management the company establishes.

Protection

5-77. Because the platoon defends to conserve combat power for use elsewhere or later, the platoon leader must secure—a tactical mission task in which a unit prevents the enemy from damaging or destroying a force, facility, or geographical location (FM 3-90)—the force. The leader enables security, by means of providing information about the activities and resources of the enemy, through the employment of reconnaissance and surveillance within its assigned AO. The leader may employ counterreconnaissance (security patrols) and establish observation posts to counter enemy reconnaissance and surveillance efforts. The platoon leader integrates platoon reconnaissance and surveillance efforts, and security patrols with those of the company information collection effort.

Active And Passive Air Defenses

5-78. In the face of an enemy air threat, the platoon usually has only active and passive (with its organic weapons) air defenses. Air defense units are usually not assigned below brigade combat team level. However, air defense assets may be located near the platoon and may provide area coverage. If air defense elements are assigned, the higher commander with the advisement of the air defense leader determines likely enemy air avenues of approach, and plans positions accordingly. The higher commander establishes priorities for protection that may include the company command post, mortar positions, and logistics assets. A stinger section may support maneuver elements from positions to the rear of defensive battle positions or along offensive attack routes as operations transition. Stinger teams on the early warning net can warn supported units of an air attack. (See ATP 3-01.8 for additional information.)

5-79. The platoon leader and subordinate leaders ensure all active and passive air defense measures are well planned and implemented, to include scanning for any hostiles mall-unmanned aircraft systems. (See Battle Drill-React to Aircraft While Dismounted, appendix E.) Passive measures include use of concealed routes and tactical assembly areas (TAAs), movement on secure routes, movement at night, increased intervals between elements of the columns, dispersion between Soldiers, using terrain to mask movement, and slowing or stopping movement to eliminate dust signature. Air guard duties assigned to specific Soldiers during dismounted (or mounted) movements and marches give each a specific search area. For movements and marches, seeing the enemy first gives the unit time to react. Leaders understand that scanning for long periods decreases the Soldier’s ability to identify enemy aircraft. During extended or long movements and marches, Soldiers are assigned air guard duties in shifts. Units take passive measures unless or until threat aircraft are within range of assigned or attached weapons, at which time when threatened they take active measures. Active measures primarily involve engaging threat aircraft with a high volume of fires with the appropriate lead applied. Active measures include use of organic and attached weapons according to the OPORD and unit SOP. (See paragraphs 4-41 to 4-44 for additional information on active and passive air defense.)

Note. Counterrocket and artillery batteries, and countermortar fire elements may be located in or near an assigned AO to support a mission. Battery sensors detect incoming rockets, artillery, and mortar shells and may be used to detect Groups 1 and 2 unmanned aircraft systems. The battery’s fire control system predicts the flight path of incoming rockets and shells, prioritizes targets, and activates in the supported AO warning system according to established ROE. Exposed elements within the AO then can take cover and provide cueing data that allows the battery’s weapon system to defeat the target before the target can impact the area. Commanders clearly define command and support relationships between counterrocket, artillery, and mortar elements and supported units during planning. (See ATP 3-01.60 for additional information on counterrocket, artillery, and mortar fires and ATP 3-01.81 for additional information on counter-unmanned aircraft system measures.)

Chemical, Biological, Radiological, And Nuclear Passive Defense

5-80. Operationally, chemical, biological, radiological, and nuclear (CBRN) passive defense enables the unit’s ability to continue military operations in a CBRN environment while minimizing the vulnerability of the force to the degrading effects of CBRN threats and hazards. Tactical-level doctrine is organized around the key activities of CBRN protection and mitigation. (See ATP 3-11.32 and ATP 3-21.10 appendix H for additional information on the CBRN environment and passive defense activities.)

Chemical, Biological, Radiological, and Nuclear Protection

5-81. CBRN protection measures are taken to keep CBRN threats and hazards from having an adverse effect on Soldiers, equipment, and facilities. Tasks that enable CBRN protection include the following:

  • Employ individual protective equipment and other CBRN protective equipment.
  • Establish CBRN alarm conditions.
  • Exercise personal hygiene and force health protection programs.
  • Utilize shielding or protective cover.

5-82. CBRN protection is an integral part of all operations. Other forms of protection involve sealing or hardening positions, protecting Soldiers, assuming appropriate mission-oriented protective posture (MOPP) levels (see table 5-2), reacting appropriately to the CBRN attack, maintaining dispersion, overhead cover (known as OHC), employment of alarms upwind, and having CBRN-trained personnel for alarms, detection, and monitoring capabilities. Individual protective items include the protective mask, joint service lightweight integrated suit technology (also known as JSLIST), overboots, and gloves. The higher-level commander above the IBCT establishes the minimum level of protection. Subordinate units may increase this level as necessary but may not decrease it. Regardless of the directed MOPP level, in the event of an actual or suspected chemical attack, Soldiers will immediately don their protective mask and then the remainder of their protective equipment to come to MOPP 4.

5-83. The JSLIST provides protection for 45 days with up to 6 launderings or up to 120 days after being removed from packaging. The JSLIST still provides protection for up to 24 hours after it is contaminated.

Table 5-2. Mission-oriented protective posture levels

5-84. Passive measures can be used to monitor for the presence of CBRN hazards. Depending on the threat and probability of use, periodic or continuous techniques are used. An area array of CBRN detectors and/or monitors can be positioned within a given area for detection and early warning of a CBRN incident.

Note. CBRN environment is an operational environment that includes CBRN threats and hazards and their potential effects. CBRN environment conditions can be the result of deliberate enemy action or the result of an industrial accident. CBRN threats include the intentional employment of, or intent to employ CBRN weapons. A CBRN hazard is a substance that could create adverse effects due to an accidental or deliberate release and dissemination. CBRN hazards may result from weapons of mass destruction employment. (See ATP 3-21.10 appendix H or FM 3-11 for additional information on CBRN hazards.)

Chemical Hazards

5-85. A chemical hazard is any chemical manufactured, used, transported, or stored that can cause death or other harm through toxic properties of those materials, including chemical agents and chemical weapons prohibited under the chemical weapons convention as well as toxic industrial chemicals. This includes—

  • Chemical weapons or toxic chemicals specifically designed as a weapon.
  • Chemical agents or chemical substance that are intended for use in military operations to kill, seriously injure, or incapacitate, mainly through physiological effects.
  • Toxic industrial chemicals are chemicals developed or manufactured for use in industrial operations or research.

5-86. A chemical weapon is a munition or device, specifically designed to cause death or other harm through the toxic properties of specified chemicals. Chemicals are released as a result of the employment of such munition or device; any equipment specifically designed for use directly in connection with the employment of munitions or devices.

5-87. A chemical agent is a chemical substance that is intended for use in military operations to kill, seriously injure, or incapacitate mainly through its physiological effects. Chemical hazards cause casualties, degrade performance, slow maneuver, restrict terrain, and disrupt operations (see table 5-3). They can cover large areas and may be delivered as liquid, vapor, or aerosol. They can be delivered by various means including artillery, mortars, rockets, missiles, aircraft spray, bombs, land mines, and covert means. (See Battle Drill-React to a Chemical Agent Attack, appendix E.)

Table 5-3. Characteristics of chemical agents

Unmasking Procedures

5-88. During an actual or suspected chemical attack, Soldiers will go to MOPP 4. Once masked, Soldiers will not unmask until there is no remaining chemical threat, and only under the approval of their commander. Soldiers will use the unmasking procedures found in paragraphs 5-89 through 5-91 to determine if it is safe to unmask.

Note. Persistent chemicals present a long-duration threat while non-persistent chemicals disperse within hours, depending on the weather.

Unmasking with M256/M256A1/A2 Kit

5-89. If an M256/M256A1/A2 detector kit is available, use it before conducing unmasking procedures. The kit does not detect all agents; therefore, proper unmasking procedures, which take approximately 15 minutes, must still be used. If all tests with the kit (including a check for liquid contamination using M8 detector paper) have been performed and the results are negative, use the following procedures:

  • The senior person should select one or two Soldiers to start the unmasking procedures. If possible, they move to a shady place; bright, direct sunlight can cause pupils in the eyes to constrict, giving a false symptom.
  • The selected Soldiers unmask for 5 minutes, then clear and reseal their masks
  • Observe the Soldiers for 10 minutes. If no symptoms appear, leaders will report the results of their unmasking procedures and request permission from higher headquarters to signal ALL CLEAR.
  • Watch all Soldiers for possible delayed symptoms. Always have first-aid treatment immediately available in case it is needed.

Note. Time to complete two simultaneous M256/M256A1/A2 detector kits, including using M8 detector paper for liquid, is approximately 20 minutes. Unmasking procedures with the M256/M256A1/A2 detector kit will take approximately 35 minutes to complete.

Unmasking without M256/M256A1/A2 Kit

5-90. If an M256/M256A1/A2 kit is not available, the unmasking procedures take approximately 35 minutes. When a reasonable amount of time has passed after the attack, find a shady area. Use M8 paper to check the area for possible liquid contamination. Conduct unmasking using these procedures:

  • The senior person selects one or two Soldiers. They take a deep breath and break their mask seals, keeping their eyes wide open.
  • After 15 seconds, the Soldiers clear and reseal their masks. Observe them for 10 minutes.
  • If no symptoms appear, the same Soldiers break their seals, take two or three breaths, and clear and reseal their masks. Observe them for 10 minutes.
  • If no symptoms appear, the same Soldiers unmask for 5 minutes, and then re-mask.
  • If no symptoms appear in 10 minutes, leaders will report the results of their unmasking procedures and request permission from higher headquarters to signal ALL CLEAR. Continue to observe all Soldiers in case delayed symptoms develop.
All-Clear Signal

5-91. Leaders initiate the request for ALL CLEAR after testing for contamination proves negative. Once approved, units pass the all-clear signal by word of mouth through their chain of command. The commander designates the specific all-clear signal and includes it in the unit SOP or the OPORD. If required, standard sound signals may be used, such as a continuous, sustained blast on a siren, vehicle horn, or similar device. When ALL CLEAR is announced on the radio, the receiving unit must authenticate the transmission before complying.

Decontamination

5-92. During continuous operations in areas of contamination, decontamination is essential in preventing casualties and severe combat degradation. The platoon gains maximum benefit from the available time and decontamination resources by observing these considerations:

  • The platoon should execute decontamination as soon as possible and as far forward as possible.
  • Decontamination should be conducted only to the extent necessary to ensure the platoon’s safety and operational readiness.
  • Decontamination priorities with regard to unit safety and mission accomplishment should be strictly observed.

5-93. These principles are consistent with doctrine that places the burden of decontamination at battalion or company level. For this reason, the platoon must develop a thorough SOP covering decontamination methods and priorities, using all available assets to the maximum extent possible. Paragraphs 5-94 to 5-101 address immediate and operational levels (see table 5-4) of decontamination. (See ATP 3-11.32 for additional information on decontamination procedures and higher level [thorough/clearance] decontamination.)

Table 5-4. Immediate and operational levels of decontamination tasks

Immediate Decontamination

5-94. Immediate decontamination minimizes casualties and limits the spread or transfer of contamination. This action is carried out by the contaminated individual and the purpose is to save lives and reduce penetration of agent into surfaces. This may includede contamination of Soldiers, clothing, and equipment (see paragraphs 5-95 to 5-98). Immediate decontamination limits casualties and permits the use of individual equipment and key systems.

5-95. Skin decontamination is a basic survival skill and should be performed within 1 minute of being contaminated. Decontaminate the eyes by flushing with water as soon as possible following contamination. Soldiers use their own reactive skin decontamination kit to decontaminate their skin and conduct personal wipe down (see paragraph 5-88). The skin decontamination kit should be stored in the individual’s mask carrier or if issued, in the individual equipment carrier bag.

5-96. Personal wipe down decontamination is performed within 15 minutes of contamination to remove contamination from individual equipment with a M295 decontamination kit. Use a chemical detector or detector paper to locate some chemical agents. Use a radiac meter to locate radiological contamination; and then brush, wipe, or shake it off.

5-97. Teams and crews use joint chemical agent detectors to monitor potential chemical contamination and then use the M100 Sorbent Decontamination System for immediate decontamination of chemically contaminated surfaces, for example, weapon systems and communications equipment. In the event of chemical or biological contamination of optics, crews conduct tactical decontamination of vision blocks and optics including machine gun and close combat missile system (known as CCMS) optics, using the M334 decontamination kit, individual equipment which augments the M295.

5-98. Operator wipe down decontamination is done within 15 minutes of contamination of surfaces that operators need to touch or contact to operate the equipment. Radiological contamination in the form of dust particles may be wiped, scraped, or brushed off. During operator wipe down, the unit or activity should use individual equipment decontamination kits.

Operational Decontamination

5-99. Operational decontamination allows a force to continue fighting and sustain momentum after being contaminated and eliminating or reducing the duration that MOPP equipment should be use.

5-100. Operational decontamination is carried out by the contaminated unit under the control of the Infantry battalion (with assistance from a higher headquarters decontamination team with an M26 Joint Service Transportable Decontamination System or support CBRN unit decontamination organization). Operational decontamination is restricted to the specific parts of contaminated, operationally-essential equipment and material to minimize contact hazards and to sustain operations.

5-101. MOPP gear exchange should be performed as mission allows, but within 24 hours of being contaminated. A MOPP gear exchange allows a unit to remove the gross contamination from Soldiers and equipment and a return to an increased operational readiness in the pursuit of mission accomplishment.

Survivability

5-102. Survivability is a quality or capability of military forces which permits them to avoid or withstand hostile actions or environmental conditions while retaining the ability to fulfill their primary mission (ATP 3-37.34), which can be enhanced through various means and methods. One way the platoon can enhance survivability when existing terrain features offer insufficient cover, protection from the effects of fires (FM 3-96), and concealment, protection from observation or surveillance (FM 3-96), is to alter the physical environment to improve cover and concealment. Similarly, natural, or artificial materials may be used as camouflage to confuse, mislead, or evade the enemy. Together, these are called survivability operations—those protection activities that alter the physical environment by providing or improving cover, camouflage, and concealment(ATP 3-37.34). Although survivability encompasses capabilities of military forces both while on the move and when stationary, survivability operations focus more on stationary capabilities—constructing fighting and protective positions and hardening facilities.

5-103. Survivability construction includes fighting positions, protective positions, and hardening. These are prepared to protect Soldiers, weapon systems, and when attached and required, vehicles. Positions can be constructed and reinforced with OHC to increase the survivability of dismounts and crew-served weapons against shrapnel from airbursts. In addition, the Infantry platoon and squad may use digging assets for ammunition caches at alternate, supplementary, or subsequent positions. All leaders must understand survivability plans and priorities. Typically, at platoon level the engineer platoon leader creates a leader’s card, which enables the platoon leader to track the survivability effort. Typically, the platoon sergeant is designated to enforce the plan and priorities and ensures the completion status is reported to the company and disseminated within the platoon, including attachments. (See section VI for a detailed discussed on fighting position construction.)

Electromagnetic Protection

5-104. One of the most recognized electromagnetic protection (EP) techniques at the small-unit tactical level is the establishment of a PACE plan. PACE plans (see paragraphs 2-34 to 2-39) should use a mix of systems that operate across a wide range of the electromagnetic spectrum to present multiple dilemmas to enemy electromagnetic warfare (EW) operators. The greatest vulnerability in a PACE plan is the failure to understand and rehearse the plan at the lowest possible level. Triggers must be established to move between PACE communications systems. This must be rehearsed continuously at all echelons during troop leading procedures (TLP). (See paragraph 2-42 for additional information on EP.)

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