Area denial weapons are used to prevent an adversary occupying or traversing an area of land. The most common are land mines of various types.
The massive use of defoliants such as Agent Orange can be considered as an interdiction measure because, at their highest concentration use they leave areas empty of any form of vegetation cover. In the desert-like terrain that ensues it is impossible for an adversary to travel without being seen, and there is nothing much left for taking cover in case of an attack.
Radiological or chemical weapons might also be considered as area denial weapons, although they are not considered militarily useful at present.
In medieval warfare sharp and sturdy stakes were buried at the bottom of long lines of ditches, with the business end up, in order to prevent cavalry charges in a given area. The correct layout of these extensive lines of ditches and the quality control of stake size, form and placement (they had to be big and sturdy enough to impale a very heavy horse) was part of the craft of war.
Areadenial weapons are used to prevent an adversary from occupying or traversing an area of land.
Most areadenial weapons pose long-lasting risks to anyone entering the area, specifically to civilians, and thus are often controversial.
Concepts for areadenial weapons which do discriminate (by active sensing) have often been proposed, but have not yet reached a stage of general usefulness, due to their high complexity (and cost) and the risk of misidentification.
Although cluster munitions were not on the formal agenda, the realisation of what had happened in Lebanon prompted a number of nations to seek to give those weapons due attention.
The use of cluster munitions on targets at long range reduces the number of enemy to be dealt with in contact battle, reduces enemy momentum, delivers shock effect and reduces the exposure of, and risk to, our front-line combat forces.
The United Kingdom believes that cluster munitions are legal weapons, that international humanitarian law is adequate to govern their use, and that the international community would be better served by implementing existing law in a consistent manner when using cluster munitions.