Improvised explosive device

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This editable Main Article is under development and subject to a disclaimer.
As with other subjects of possible terrorist use, this article gives capabilities and policies and general technical characteristics, but deliberately does not go into detailed operational usage techniques. Do not attempt to use any device described here. If you are threatened by one, move away from it and call the appropriate civilian or military emergency response agency.

An improvised explosive device (IED) is a destructive device, including an explosive but also possibly incendiary or toxic materials, and perhaps with mechanical components to increase fragmentation or armor penetration, which is not a purpose-designed, factory built weapon built to military standards. It is a subset of boobytraps, which do not always include explosives. Often, the explosive component comes from captured military supplies; a common IED in the Iraq War consists of an improvised trigger that fires Iraqi or U.S. artillery shells.

They divide into a variety of types, based on the means used to bring it to the target.


  • Disguised, static IEDs
    • victim operated IED; the classic boobytrap in which the victim actuates the detonator by an action such as stretching a tripwire, lifting an object that is inhibiting a pressure-release fuze, etc.
  • Disguised, moveable IEDs
    • vehicle-borne improvised explosive devices [VBIEDs]
    • suicide bomber vests, victim-actuated IEDs, or remote-controlled cars)
  • Thrown or projected IEDs (improvised grenades or mortars), used mostly from overhead passes.
  • Concealed but not disguised: IEDs placed in, on, or under a target or in or under unsecured vehicles.
  • Hoax IED[1]


IEDs and Weapons of Mass Destruction

Some legal codes, especially in the U.S., have started to treat large explosives as weapons of mass destruction. While, indeed, a large high explosive such as the truck bomb (VBIED) used in the Oklahoma City bombing destroyed a large office building and caused 168 deaths and many more casualties, WMDs, for years, have been defined as weapons whose effect is greater than that of an equivalent weight of high explosives. By that criterion, calling a large amount of high explosives "WMD" confuses a longer-established definition.

In Iraq, there have been some IEDs that met the technical definition of WMDs, because they put high explosives on a commercial tank truck filled with chlorine, an industrial chemical that has been used as a chemical weapon. The IED, however, did not disperse the poison efficiently, and the chemical effects were less than the explosive effects.

A terrorist-built nuclear weapon, however, could indeed be both an IED and WMD.

Large IEDs

While many IEDs are comparable in blast power to man-portable grenades, mines and artillery shells, some VBIEDs have been quite large. Examples well-known in the West, not intending to deprecate the human cost of lesser-known events in places such as the Iraq War, insurgency, include:

Small IEDs

A commonly improvised device, often known as a 'Molotov Cocktail' or the more descriptive 'Petrol Bomb', is an incendiary. Glass bottles are filled with petrol and then stuffed with an improvised fuse. The device is then thrown at a target and, when the bottle shatters, the main contents are ignited on impact. The petrol can be mixed with other substances to help extend the life of the fire and make the substance stick better to targets. Petrol bombs have been used extensively by Republicans in Northern Ireland, during rioting since the 1970s. Large numbers of glass milk bottles, which were usually returned, washed and refilled, disappeared and were stored by various factions during the height of the Troubles.

Another type of improvised explosive device in Northern Ireland made use of the existing timer technology of parking metres, resulting in the withdrawal of mechanicaly-timed parking metres from that part of the country.

Other small improvised explosives include nail bombs, pipe bombs and letter bombs.

Increasing effect

The simplest way to increase effect, of course, is to use more explosive. Nevertheless, this is not always practical, especially when the explosives must be hand-carried. Other techniques have been used.

  • Boosting. Buried mines, or other explosive devices are stacked on top of one another. The topmost explosives are non-metal, and only the device buried deepest from the surface is fused; the lower explosives fire from sympathetic detonation. This reduces the probability of detection, and it increases the force of the blast.
  • Coupling. Coupling is a method of linking one mine or explosive device to another, usually with detonating cord. This technique is often used todefeat countermeasure equipment. A heavy mine roller will pass over the initial, unfused device and set off the second fused device. This in turn detonates the overpassed device underneath the clearing vehicle.
  • Daisy chaining. IEDs may be linked together along a roadway with trip wire or detonating cord. When the initial mine is detonated, the other mines also detonate.
  • Explosively formed projectiles
  • Industrial chemicals or radioisotopes: IEDs in Iraq have been attached to commercial trucks carrying chlorine gas; other industrial toxic chemicals or radioactive materials could be used