Area denial weapon
An area denial weapon is a defensive device used to prevent an adversary from occupying or traversing an area of land, sea or air. The specific method may not be totally effective in preventing passage, but is sufficient to severely restrict, slow down, or endanger the opponent. Some area denial weapons pose risks to civilians entering the area even long after combat has ended, and consequently are often controversial. An area denial weapon can be part of an anti-access/area denial (A2/AD) strategy.
Historical methods[edit]
Anti-cavalry[edit]
In medieval warfare, sturdy stakes were stuck into the ground at the bottom of long lines of ditches, positioned with a sharp end pointing up diagonally, in order to prevent cavalry charges in a given area. Even if the stakes were spotted, horsemen would be forced to dismount and effectively give up their advantage as cavalry, and become easier targets. The correct layout of these extensive lines of ditches and the control of stake size, form and placement were part of the craft of war.
An alternative cavalry deterrent, allowing quicker dispersal and providing the advantage of being hidden more easily, was the deployment of, for example, small balls with spikes, used during most of antiquity. Many variants were used, such as boards with metal hooks, as described as used by Julius Caesar.[1] A more modern version of this are caltrops.
Passive fortification—ditches and obstacles such as dragon's teeth and Czech hedgehogs—were used as anti-tank measures during World War II.
Anti-infantry[edit]
Simple rows or clusters of sharpened sticks (nowadays also known as punji sticks), and small caltrops have been used in anti-infantry warfare since antiquity. However, due to the difficulty of mass-producing them in the pre-modern age, they were rarely used except in the defense of limited areas or chokepoints, especially during sieges, where they were used to help seal breaches. Increasing ease of production still did not prevent these methods from slowly falling out of favor from the late Middle Ages onward.[1]
Caltrops are still sometimes used in modern conflicts, such as during the Korean War, where Chinese troops, often wearing only light shoes, were particularly vulnerable.[1] In modern times, special caltrops are also sometimes used against wheeled vehicles with pneumatic tires. Some South American urban guerrillas such as the Tupamaros and Montoneros, who called them "miguelitos," have used caltrops to avoid pursuit after ambushes.[2]
Drawbacks[edit]
As area denial weapons do not discriminate between friend, foe, or civilian, they make the affected zone hazardous for all trying to enter. Concepts for area denial 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.
Explosive-based area-denial weapons (mines) may be intentionally equipped with detonators which degrade over time, either exploding them or rendering them relatively harmless. Even in these cases, unexploded munitions often pose significant risk.
