Area denial weapon An area denial weapon is a device used to prevent an adversary from occupying or traversing an area of land . The specific method used does not have to be totally effective in preventing passage ( and sometimes is not ) as long as it is sufficient to severely restrict , slow down , or endanger the opponent . Most area denial weapons pose long - lasting risks to anyone entering the area , specifically to civilians , and thus are often controversial . Historical methods . In the 18th century , Spanish bayonet ( probably the locally - common species " Yucca aloifolia " ) was planted around the fortifications of St . Augustine , Florida to discourage penetration by both man and beast . Anti - cavalry . In medieval warfare , sharp and sturdy stakes were buried at the bottom of long lines of ditches , pointed end up diagonally , in order to prevent cavalry charges in a given area . Even if the stakes were spotted , soldiers would be forced to dismount and effectively give up their purpose as cavalry as well as becoming easier targets . The correct layout of these extensive lines of ditches and the quality control of stake size , form and placement was part of the craft of war . A more modern version , allowing quicker dispersal and providing the advantage of being hidden easier , are caltrops , though items bearing close similarity ( small balls with spikes ) had been in use for most of antiquity . Many variants were also used , such as boards with metal hooks , as described during battles of Julius Caesar . Passive fortification — ditches and obstacles such as dragon ' s teeth , Czech hedgehog s and Toblerones — were used as anti - tank ( the modern ' cavalry ' ) measures during World War II . Anti - infantry . Simple rows or clusters of sharpened sticks ( nowadays also known as punji stick s ) , and the use of small caltrops have been a feature of anti - infantry warfare for a long time . 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 . 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 . In modern times , special caltrops are also sometimes used against wheeled vehicles with pneumatic tires . Some South American urban guerrillas as the Tupamaros and Montoneros called them " miguelitos " and used these as a tactic to avoid pursuit after ambushes . Modern methods . Explosives . The most common are land mine s of various types , planted by hand or dispersed by artillery . Some modern prototypes experiment with automatic guns or artillery - delivered ammunitions that are fired only after remote sensing detects enemies . Booby traps or improvised explosive device s in sufficient concentration also qualify as area denial weapons , though they are much easier to clear and usually pose less long - term danger . During an armed conflict there are several methods of countering land mines . These include using armoured vehicles to negate the effects of anti - personnel land mines . Land mines can also be cleared either by hand , or by using specialised equipment such as tanks equipped with flail s . Explosives can also be used to clear mine fields , either by artillery bombardment , or with specialised charges such as Bangalore torpedo s , the Antipersonnel Obstacle Breaching System and the Python Minefield Breaching System . 156 states are parties to the Ottawa Treaty under which they have agreed not to use , stockpile , produce or transfer anti - personnel mines . Anti - ship missiles are a modern method of stopping a potential adversary from attacking by sea . China , North Korea , Syria and Iran all have developed or imported such weapons in an effort to develop a modern anti - access or A2 / AD strategy to counter modern United States weaponry . NBC agents . Various NBC ( nuclear , biological , chemical ) weapons can be used for area denial , as long as the agent is long - lasting . Fallout from nuclear weapons might be used in such a role . While never actually employed in this form , its use had been suggested by Douglas MacArthur during the Korean War . Anthrax spores can contaminate the ground for long periods of time , thus providing a form of area denial . However , the short - term ( tactical ) effects are likely to be low - the psychological effects on an opponent would likely be more significant . The massive use of defoliants such as Agent Orange can be used as an interdiction measure because 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 little cover in case of an attack , especially from the air . Many chemical weapons also produce toxic effects on any personnel in an affected area . However , this usually has no tactical value , as the effects of indirect exposure do not develop fast or substantially enough - though again , the psychological effect upon an enemy aware of the chemical usage may be considerable . There are however some chemical agents that are by design non - degrading , such as the nerve agent VX . Sulfur mustard was extensively used by both German and allied forces on the west front in World War I as an effective area - denial weapon , usually through contaminating large land stripes by extensive shelling with HD / Gelbkreuz ordnance . Since sulfur mustard is very persistent , involatile , hard - to - decontaminate and highly effective in inflicting debilitating casualties at even low doses , this tactic proved to be very effective . Targeted . To address some of the problems with land - mines ( see ' Drawbacks ' ) , weapons manufacturers are now experimenting with area - denial weapons which need human command to operate . Such systems are usually envisioned as a combination of either explosives , pre - targeted artillery shelling or smartgun s with remote sensing equipment ( sound , vibration , sight / thermal ) . By not posing a long - term risk , and by having some level of IFF capability ( automatic or human - decision - based ) , these systems aim to achieve compliance with the Ottawa Treaty , as for example the Metal Storm ADWS ( Area Denial Weapons System ) . Drawbacks . As area denial weapons do not discriminate between friend and foe ( or civilians ) 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 detonator s which degrade over time , either exploding them or rendering them ( relatively ) harmless . Even in these cases , unexploded munitions often pose significant risk .