H-14. Suppress, obscure, secure, reduce, and assault (SOSRA) are the breaching fundamentals being applied to ensure success when breaching against a defending enemy. These obstacle reduction fundamentals always will apply, but they may vary based on METT-TC.
H-15. Suppression is a tactical task used to employ direct or indirect fires or an electronic attack on enemy personnel, weapons, or equipment to prevent or degrade enemy fires and observation of friendly forces. The purpose of suppression during breaching operations is to protect forces reducing and maneuvering through an obstacle. Suppression is a mission-critical task performed during breaching operation. Suppression generally triggers the rest of the actions at the obstacle. Fire control measures ensure all fires are synchronized with other actions at the obstacle. Although suppressing the enemy overwatching the obstacle is the mission of the support force, the breach force should provide additional suppression against an enemy the supporting force cannot suppress.
H-16. Obscuration must be employed to protect forces conducting obstacle reduction and passage of assault forces. Obscuration hampers enemy observation and target acquisition by concealing friendly activities and movement. Obscuration smoke deployed on or near the enemy’s position minimizes its vision. Screening obscurants employed between the reduction area and the enemy conceals movement and reduction activities. It also degrades enemy ground and aerial observations. Obscuration must be planned carefully to provide maximum degradation of enemy observation and fires, but it must not degrade friendly fires and control significantly.
H-17. Friendly forces secure reduction areas to prevent the enemy from interfering with obstacle reduction and passage of the assault force through lanes created during the reduction. Security must be effective against outposts and fighting positions near the obstacle and against overwatching units as necessary. The far side of the obstacle must be secured by fires or be occupied before attempting efforts to reduce the obstacle. The attacking unit’s higher headquarters is responsible for isolating the breach area by fixing adjacent units, attacking enemy reserves in-depth, and providing counterfire support.
H-18. Identifying the extent of the enemy’s defenses is critical before selecting the appropriate technique to secure the point of breach. If the enemy controls the point of breach and cannot be suppressed adequately, the force must secure the point of breach before it can reduce the obstacle.
H-19. The breach force must be resourced with enough maneuver assets to provide local security against the forces supporting force cannot engage sufficiently. Elements within the breach force securing the reduction area also may be used to suppress the enemy once reduction is complete. The breach force also may need to assault to the far side of the breach and provide local security so the assault element can seize its initial objective.
H-20. Reduction is the creation of lanes through or over an obstacle to allow an attacking force to pass. The number and width of lanes created varies with the enemy situation, the assault force’s size, composition, and scheme of maneuver. The lanes must allow the assault force to rapidly pass through the obstacle. The breach force will reduce proof (if required), mark, and report lane locations and lane-marking method to higher command headquarters. Follow-on units will reduce or clear the obstacle when required. Reduction cannot be accomplished until suppression and obscuration are in place, the obstacle has been identified, and point of breach is secure.
H-21. A breaching operation is not complete until: