Improvised explosive device
An improvised explosive device is a bomb constructed and deployed in ways other than in conventional military action. It may be constructed of conventional military explosives, such as an artillery shell, attached to a detonating mechanism. IEDs are commonly used as roadside bombs, or homemade bombs.
The term "IED" was coined by the British Army during the Northern Ireland conflict to refer to booby traps made by the IRA, and entered common use in the U.S. during the Iraq War.
IEDs are predominantly utilized by violent non-state actors, such as guerrilla or terrorist organizations, who use them in the context of strategies and tactics of insurrection, guerrilla warfare, asymmetric warfare, urban warfare or in terrorist operations. IEDs can also be utilized by state special forces or commando forces, to conduct unconventional warfare in a theatre of operations, such as in the case, for example, of the United States Army Special Forces.
Background
An IED can be defined as a device placed or fabricated in an improvised manner incorporating destructive, lethal, noxious, pyrotechnic or incendiary chemicals and designed to destroy, incapacitate, harass or distract; it may incorporate military stores, but is normally devised from non-military components. IEDs may incorporate military or commercially sourced explosives, and often combine both types, or they may otherwise be made with homemade explosives.An IED has generally five components: a switch, an initiator, container, charge, and a power source ; an IED designed for use against armoured targets such as personnel carriers or tanks will be designed for armour penetration, by using, for example, a shaped charge that creates an explosively formed penetrator; IEDs are extremely diverse in design and may contain many types of initiators, detonators, penetrators, and explosive loads. Some particularly sophisticated IEDs can also incorporate anti-handling or anti-defusing systems: this was the case, for example, of the IED prepared by John Birges in 1980, used in an extortion attempt against the Harvey's Resort Hotel.
File:IED Jerusalem 2009 09 08 05.JPG|left|thumb|A modified gas cylinder, packed with explosive and pieces of rebar used as shrapnel, dissected for display.
Antipersonnel IEDs typically also contain fragmentation-generating objects such as nails, ball bearings or even small rocks to cause wounds at greater distances than blast pressure alone could. Injuries caused by antipersonnel improvised explosive devices to dismounted soldiers and civilians were reported in BMJ Open to be far worse than those caused by conventional antipersonnel mines, resulting in multiple limb amputations and lower body mutilation. This combination of injuries has been given the name "Dismounted Complex Blast Injury" and is thought to be the worst survivable injury ever seen in war.
IEDs are triggered by various methods, including remote control, infrared or magnetic triggers, pressure-sensitive bars or trip wires. In some cases, multiple IEDs are wired together in a daisy chain to attack a convoy of vehicles spread out along a roadway.
IEDs made by inexperienced designers or with substandard materials may fail to detonate, and in some cases, they detonate on either the maker or the placer of the device. Some groups, however, have been known to produce sophisticated devices constructed with components scavenged from conventional munitions and standard consumer electronics components, such as mobile phones, washing machine timers, pagers, or garage door openers. The sophistication of an IED depends on the training of the designer and the tools and materials available.
IEDs may use artillery shells or conventional high-explosive charges as their explosive load as well as homemade explosives. However, the threat exists that toxic chemical, biological, or radioactive material may be added to a device, thereby creating other life-threatening effects beyond the shrapnel, concussive blasts and fire normally associated with bombs.
It is possible to categorize IEDs by warhead, by delivery mechanism, by trigger mechanism:
By warhead
The Dictionary of Military and Associated Terms includes two definitions for improvised devices: improvised explosive devices and improvised nuclear device. These definitions address the Nuclear and Explosive in CBRNe. That leaves chemical, biological and radiological undefined. Four definitions have been created to build on the structure of the JCS definition. Terms have been created to standardize the language of first responders and members of the military and to correlate the operational picture.General-purpose explosive charges
An IED may be equipped with a general-purpose explosive charge, designed to project a blast wave, with or without additional shrapnel materials, all around itself, for the purpose of inflicting damage to peoples and unarmored targets. Examples of such charges are those contained in IEDs such as pipe bombs, nail bombs, tin can grenades, pressure cooker bombs, car bombs, and so on.In general, the nature and potential of the explosive substances contained in an IED – both in terms of the main explosive charge and the detonator – is extremely variable: military explosives obtained from modern conventional munitions, such as trinitrotoluene, Composition B, RDX, pentaerythritol tetranitrate ; commercial or improvised explosives, such as dynamite, ammonium nitrate and fuel oil, urea nitrate, chlorate/perchlorate mixtures, nitrate- and peroxide-based mixtures and compounds, triacetone triperoxide, hexamethylene triperoxide diamine.
Directionally focused explosive charges
An IED may be equipped with a directionally focused explosive charge, designed to channel most of the force of the explosion in a single direction. Such IEDs are specifically built to be employed in an anti-personnel or anti-tank/anti-material role.Examples of anti-personnel IEDs of this category are the fougasse and the grapeshot charge.
A fougasse is an improvised mortar capable of a single discharge, constructed by making a hollow in the ground or rock, placing an explosive charge at the bottom of it, then covered with various types of projectiles ; the hollow is camouflaged in the surrounding environment; the fougasse is then fired by means of a fuse or electrically, resulting in the projectiles to be scattered in front of it, along the axis of the excavation of the hollow. An IED with ancient origins, the fougasse was used in warfare – even in a configuration capable of launching incendiary liquids – at least until the Second World War and the Korean War.
A grapeshot charge employ the same general operating principle of the fougasse, but more closely resembling an improvised Claymore mine, also made for directional fragmentation. It is constructed by inserting its major components – projectiles, buffer material, explosive charge and blasting cap – in a portable container, such as a metal tube, an ammo can or a No. 10 can. The trajectory of the multiple projectiles – usually nails, bolts, nuts, ball bearings, glass, small pieces of scrap metal, rocks and other similar shrapnel materials – is flat, as if they were fired from a shotgun.
Examples of anti-tank/anti-material IEDs of this category are the shaped charge, the explosively formed penetrator/projectile and the platter charge.
A shaped charge concentrate the energy released by the explosion on a small area, making a tubular or linear fracture in the target; to do so, it present a cavity, usually cone-shaped and lined. The cavity liner can be made from copper, tin, zinc, or glass. The high-explosive charge is placed at a very short distance from the target – but still kept at an adequate standoff distance – with the cavity facing the target. When the charge is detonated, the shock wave propagates from the detonator towards the cone-shaped cavity, thus producing a piercing jet of particles at high speed, temperature and pressure, capable of perforating concrete and armor, but wich loses effectiveness after a short distance. Historical examples of improvised shaped charges are those devised by the Viet Cong during the Vietnam War, which were incorporated into various types of improvised weapons, such as bounding anti-tank/anti-vehicular mines, demolition charges and anti-tank hand grenades.
An explosively formed penetrator/projectile is a special type of shaped charge; also cylindrical, it incorporate a thicker and heavier metal liner, usually a plate made of stamped or machined copper, with a concave lens or dish shape, pointed inward. The plate is aimed at the target. When the high-explosive charge, uniformly packed behind the liner/plate, is detonated, the liner/plate is formed into a projectile called “slug” or “penetrator”, which is propelled toward the target at an extremely high velocity. The difference in the shape and weight of the liner allows an EFP to be effective at long standoffs from the target, thus making it deployable from a greater distance than a traditional shaped charge. The “slug” produced by an EFP is capable of penetrating, from a distance, armoured targets like tanks, however, the accuracy of such devices is limited, due to the way in which EFPs are produced: the “slug” projected from the explosion has no stabilization because it has no tail fins and it does not spin like a bullet from a rifle. This type of IED was used by insurgent forces in recent conflicts, such as the Iraq War, with lethal effects.
A platter charge, also made for target penetration, is similar to EFPs, serving a similar role as an EFP but with reduced effect and easier construction: the main differences being that the explosive charge do not have a cavity, and that the plate is flat and not concave, not made with machined copper but with cheaper cast or cut steel; in this case too the plate is launched by the force of the explosion – as a single projectile or "slug" – in a single direction.