Fire directed to an area to keep the enemy from using that area.
Interdiction fires are used to disrupt, delay, and destroy enemy forces that cannot fire their primary weapon system on friendly forces because of range limitations or intervening terrain. Field artillery cannon and missile battalions are responsible for most ground interdiction fires. Mortar sections and platoons fire limited, specific types of interdiction fires on likely or suspected enemy assault positions or assembly areas. As the advancing US forces close on an objective, mortar fires can be shifted from preparatory or suppressive fire (close support fires) to interdiction fires targeted on likely enemy withdrawal routes or suspected rally points. Normally, the benefits gained from unobserved mortar interdiction fire intended to harass the enemy do not outweigh the costs of ammunition expended and the increased danger of counterfire. Dismounted infantry, decisively engaged with an enemy on close terrain, can employ harassment and interdiction fire to its advantage. In some cases, when the enemy avenue of approach is canalized within deep defilade, such as a ravine or a street between high buildings, mortar interdiction fire may be the only way to attack him.