MCRP 12-10B.1, page 95

Clearing fields of fire Laying mines Preparing routes to the rear Preparing fighting positions. (a) Employment of Obstacles. Obstacles are used to shape the battlespace. (See FM 5-102, Countermobility, and FM 20-32, Mine/Countermine Operations, for details.) The four types of obstacles are: Disrupting. Disrupting obstacles are used to disrupt the enemy’s timetable and force him/her into conducting a time-costly bypass or breach, or cause his/her march columns to become staggered or “telescoped.” Turning. Turning obstacles are used to canalize the enemy into engagement areas or kill zones where combined-arms fires can be concentrated and flanking shots are increased. Fixing. Fixing obstacles increase the time the enemy can be fired on in an engagement or target area and to cause increased confusion. Blocking. Blocking obstacles prevent or delay the enemy from moving past a certain point. (b) Obstacle Belts. In defensive obstacle planning, obstacles may be emplaced in a series of belts. This enhances the overall effectiveness of the obstacle plan with successive belts designed for specific purposes. The following example lays out a three-belt obstacle plan. 1 First Obstacle Belt. The first obstacle belt is enplaced at the nearest buildings across from and parallel to the main defensive position. This belt consists of wire and improvised barriers (including inside buildings, in subterranean avenues of approach, and outside in open areas), danger areas, and dead space. These barriers and obstacles should be heavily boobytrapped and covered by fires. This belt is designed to impede enemy movement, breaks up and disorganize attack formations, and inflicts casualties. 2 Second Obstacle Belt. The second obstacle belt is placed between the first belt and the main defensive position buildings, but out of hand grenade range. It is designed to impede movement, canalize the enemy into the best fields of fire, break up attack formations, and inflict casualties. This belt is not meant to stop the enemy permanently. It consists mainly of wire obstacles, improvised barriers, road MCWP 3-35 .3 3-24