3-91. Security in the defense includes all active and passive measures taken to avoid detection by the enemy, deceive the enemy, and deny enemy reconnaissance elements accurate information on friendly positions. The two primary tools available to the platoon leader are observation posts and patrols. In planning for the security in the defense, the platoon leader considers the military aspects of terrain: observation and fields of fire, avenues of approach, key terrain, obstacles and cover, and concealment. He uses his map to identify terrain that will protect the platoon from enemy observation and fires, while providing observation and fires into the engagement area. He uses intelligence updates to increase his situational understanding, reducing the possibility of the enemy striking at a time or in a place for which the platoon is unprepared.
3-92. Current mission commands systems allow mechanized squads to digitally transmit enemy situation and observation reports. This simplifies the reporting process without compromising security. Dismounted observation posts still render reports by frequency modulation radio transmission.
3-93. An observation post provides the primary security in the defense. Observation posts provide early warning of impending enemy contact by reporting direction, distance, and size. It detects the enemy early and sends accurate reports to the platoon. The platoon leader establishes observation posts along the most likely enemy avenues of approach into the position or into the area of operation. Leaders ensure that observation posts (mounted or dismounted) have communication with the platoon.
3-94. Early detection reduces the risk of the enemy overrunning the observation post. Observation post may be equipped with a Javelin command launch unit; class 1 unmanned aircraft system; seismic, acoustic, or frequency detecting sensors to increase its ability to detect the enemy. They may receive infrared trip flares, infrared parachute flares, infrared M203 or M320 rounds, and even infrared mortar round support to illuminate the enemy. The platoon leader weighs the advantages and disadvantages of using infrared illumination when the enemy is known to have night vision devices that detect infrared light. Although infrared and thermal equipment within the platoon enables the platoon to see the observation post at a greater distance, the observation post should not be positioned outside the range of the platoon’s small-arms weapons.
3-95. To further reduce the risk of fratricide, observation posts use GPS to navigate to the exit and entry point in the platoon’s position. The platoon leader ensures he submits an observation post location to the company team commander to ensure a no fire area is established around each observation post position.
3-96. Platoons actively patrol in the defense. Patrols enhance the platoon’s ability to fill gaps in security between observation posts. The platoon leader forwards his tentative patrol route to the commander to ensure they do not conflict with other elements within the company team. The commander forwards the entire company team’s patrol routes to the task force. This allows the operations and intelligence staff officers to ensure all routes are coordinated for fratricide prevention and no gaps are present. The patrol leader may use a GPS to enhance his basic land navigational skills as he tracks his patrol’s location on a map, compass, and pace count or odometer reading.
VEHICULAR FIRING POSITION
3-97. After a range card is completed, the position should be marked with ground stakes. This enables the vehicle or a replacement vehicle to reoccupy the position and to use the range card data. The steps in marking a vehicle position are staking the position and moving into position. Each are described below.
Stake the Position
3-98. Before the vehicle is moved, the position should be staked. Three stakes must effectively mark the position as shown in figure 3-10.
Figure 3-10. Stake the position
3-99. One stake is placed in front of the vehicle, centered on the driver’s station and just touching the hull. The stake should be long enough for the driver to see it when in position. The other two stakes are placed parallel to the left track and lined up with the hub on the front and rear wheels. The stakes should be placed close to the vehicle with only enough clearance to move the vehicle into position.
3-100. The stakes should be driven firmly into the ground. Engineer tape or luminous tape can be placed on the friendly side of the stakes so that the driver can see them. A rock is placed at each of the front two corners of the vehicle to assist in reoccupation if the stakes are lost.
Move into Position
3-101. If the situation permits, a ground guide can be used to assist the driver. If a ground guide cannot be used, the driver moves the vehicle in, parallel to the side stakes, with the front stake centered on the driver’s station. Once the vehicle is in position, the gunner should index the range and azimuth for one of the TRPs on the range card. If the sight is aligned on the TRP, the vehicle is correctly positioned. If the sight is not aligned on the TRP, the gunner should tell the driver which way to move the vehicle to align the sight on the target. Only minor adjustments should be necessary. If the stakes are lost and the position is not otherwise marked, the vehicle is moved to the approximate location. The vehicle commander or gunner can use a compass to find the left and right limits. The vehicle should be moved if time allows until it is within 6 to 8 inches of exact position.