A major cause of coalition casualties in Iraq has been roadside bombs (IEDs, or Improvised Explosive devices). These bombs use military explosives or munitions (artillery and mortar shells) stolen from Iraqi ammo dumps starting in early 2003. The explosives are set off using commercial blasting caps or detonator cord. The detonation is most commonly controlled remotely with a variety of wireless devices. These range from remote control toys (with a range of about 100 meters), to transceivers (with a range of five kilometers). Also used are car alarm and keyless entry systems (with a range of 200 meters), wireless doorbells (200 meters), cordless phones (100 meters) and cell phones (two kilometers). Less frequently, the detonation is set off via a wire to an electrical device. Even more rare are timers and booby-trapped devices. Wire has become more popular lately, as more coalition convoys carry electronic jammers that render wireless detonation systems useless.

Almost all the IEDs are found in Sunni Arab areas. The highest incidence of attacks are between 9 AM and noon. The lowest is between midnight and 6 AM. A great deal of ingenuity has gone into rigging the wireless devices and the explosives. The people doing this are Iraqi military people who used to work for Saddam. This sort of improvisation was seen during the 1991 war. Throughout the 1990s, Iraqis were quick to improvise with their air defense and radar systems in an attempt to bring down one of the American or British warplanes patrolling the no-fly zone. They never succeeded, but some of the attempts were quite clever. Documents captured during, and after, the war, gave more details of this guerilla war effort by the Baath Party, as part of a grand plan to regain control of Iraq for the Sunni Arabs. So far, the IEDs have killed hundreds of Americans, but have not had the desired effect on the new Iraqi government. Countermeasures against the IED campaign has been very successful, with over 90 percent of the IEDs found and destroyed.