SECURITY FUNDAMENTALS

D-4. The techniques employed to secure a larger unit are generally the same as those of the offense and defense. It is the application of those techniques that differ. Table D-1 lists the most common techniques used, information required executing the operation, and principles used to employ them.

SCREEN

D-5. A screen primarily provides early warning to the main body. A unit performing a screen observes, identifies, and reports enemy actions. Screen is defensive in nature but not passive in execution. It is employed to cover gaps between forces, exposed flanks, or the rear of stationary or moving forces. Generally, a screening force fights only in self-defense. However, it may engage enemy reconnaissance elements within its capability (counterreconnaissance). A screen provides the least amount of protection of all security missions. It does not have the combat power to develop the situation. It is used when the likelihood of enemy contact is remote, the expected enemy force is small, or the friendly main body needs only a minimum amount of time once it is warned to react

D-6. Screen tasks are to─

• Allow no enemy ground element to pass through the screen undetected and unreported.
• Maintain continuous surveillance of all avenues of approach larger than a designated size into the area under all visibility conditions.
• Destroy or repel all enemy reconnaissance patrols within its capabilities.
• Locate the lead elements of each enemy advance guard and determine its direction of movement in a defensive screen.
• Maintain contact with enemy forces and report all activities in the area of operations.
• Maintain contact with the main body and security forces operating on its flanks.
• Impede and harass the enemy within its capabilities while displacing.

Stationary Screen
D-7. When tasked to conduct a stationary screen (see figure D-1), the leader first determines likely avenues of approach into the main body’s perimeter. The leader determines the location of potential observation posts along these avenues of approach. Ideally, the leader assigns observation posts in-depth if he has the assets available. If necessary, he identifies additional control measures (named areas of interest, phase lines, TRP, or checkpoints) to assist in controlling observation, tracking of the enemy, and movement of his own forces. The unit conducts mounted and foot patrols to cover ground not being observed from observation posts. Once the enemy is detected from an observation post, the screening force may engage him with indirect fires. This prevents the enemy from penetrating the screen line and does not compromise the location of the observation post. If enemy pressure threatens the security of the screening force, the unit reports the situation to the controlling headquarters and requests permission to displace to a subsequent screen line or follow-on mission.

Moving Screen
D-8. Platoons may conduct a moving screen to the flanks or rear of the main body force. The movement of the screen is tied to time and distance factors associated with the movement of the friendly main body.

D-9. Responsibilities for a moving flank screen begin at the front of the main body’s lead combat element and end at the rear of the protected force. In conducting a moving flank screen, the unit either occupies a series of temporary observation posts along a designated screen line to overwatch the main body, or if the main body is moving too fast, continues to move while maintaining surveillance. The screening force uses one or more of the three basic movement techniques to control movement along the screened flank (traveling, traveling overwatch, and bounding overwatch).

GUARD

D-10. A guard differs from a screen in a guard force contains sufficient combat power to defeat, cause the withdrawal of, or fix the lead elements of an enemy ground force before it can engage the main body with direct fires. A guard force uses all means at its disposal, including decisive engagement, to prevent the enemy from penetrating the security zone. It operates within the range of the main body’s indirect fire weapons, deploying over a narrower front than a comparable-size screening force to permit concentrating combat power. The three types of guard operations are: advance; flank; and rear guard.

D-11. Platoons as part of a company can be assigned a guard mission conduct all of the measures associated with a screen. Additionally they─

• Destroy the enemy advance guard.
• Cause the enemy main body to deploy, report its disposition, composition, strength, and capabilities.

COVER

D-12. The covering force, or portions of it, often becomes decisively engaged with enemy forces. Therefore, the covering force must have substantial combat power to engage the enemy and accomplish its mission. The platoon along with the company team may participate in covering force operations but does not conduct them on its own. The covering force develops the situation earlier than a screen or a guard force. It fights longer and more often and defeats larger enemy forces.

AREA SECURITY

D-13. Area security is used by units to secure their area of operation from smaller enemy units (special purpose forces, guerrillas).

D-14. During area security operations civilians will be present. Therefore, leaders must ensure Soldiers understand current ROE. However, leaders always are responsible for protecting their forces and consider this responsibility when applying the ROE. Restrictions on conducting operations and using force must be explained clearly and understood by everyone. Soldiers must understand their actions, no matter how minor, may have far-reaching positive or negative effects. They must realize both friendly or hostile media and adversary information activities quickly can exploit their actions, especially the manner in which they treat the civilian population.

D-15. Leaders executing area security measures in a densely populated area must assess the effect of imposing a degree of control on both traffic and pedestrians carefully. For instance, during the rush hour period, however efficient the traffic control point, a crowd of impatient civilians or cars and trucks can quickly build-up and precipitate the very situation the traffic control point leader is trying to avoid.

D-16. Population and resource control operations cause inconvenience and disruption to all aspects of community life. Therefore, it is important members of the civil community appreciate the purpose of such operations. In particular, they must understand control measures are protective and not punitive. All personnel involved in operations designed to ensure security must be thoroughly conversant with their duties and responsibilities. They must be able to work quickly and methodically to prevent delay and disruption to legitimate activities. They also must work to avoid unnecessary damage to personnel, vehicles, and property. To achieve their purpose they must be thorough. Leaders, at all levels, must ensure adequate security is in place to counter all assessed risks.

LOCAL SECURITY

D-17. Local security prevents a unit from being surprised and is an important part of maintaining the initiative. Local security includes local measure taken by units against enemy actions. It involves avoiding detection by the enemy or deceiving the enemy about friendly positions and intentions. It also includes finding any enemy forces in the immediate vicinity and knowing as much about their positions and intentions as possible. The requirement for maintaining local security is an inherent part of all operations. Table D-2 lists a sample of active and passive local security measures.