HISTORY AND GENERAL DISCUSSION
This is a type of IED used by insurgent groups such as Al Qaeda in Iraq,
Hezb-i-Islami, and various Al Qaeda affiliates in Iraq and
Afghanistan. Their introduction in those conflicts was a direct
response to the fielding of the M1185 HMMV (also known colloquially as
the up-armored HMMV by members of the U.S. Marines and Army) and the MRAP family of vehicles designed to withstand
significant explosive blasts.
Explosively Formed Penetrators have also been used by the German terrorist organization Red Army Faction, Hezbollah, and the United States Military as a part of demolition operations. Although the technology is not new, their increasing prevalence is of great concern among ground forces in Iraq and Afghanistan. Considerable training is conducted for all U.S. personnel entering the CENTCOM AOR concerning IED and EFP-IED threats.
CONSTRUCTION AND COMPOSITION
Explosively formed penetrators are typically referred to by members of coalition and NATO forces operating in Afghanistan and Iraq as EFP's. Their typical construction is that of a precision-machined conical copper disc in front of a package of high explosives, also known as a shaped charge. This is typically RDX, C4, SEMTEX, or some other military-grade explosive. On detonation, the explosive causes the copper cone or dome to be projected out into a hypervelocity jet of molten metal. Variations on warhead design include:
- SEFP: Single Explosively Formed Penetrator. Single copper plate designed for armor penetration, produces a long jet of copper that breaks up on impact with target.
- MEFP: Multiple Explosively Formed Penetrator. Single copper plate with surface structural differences (usually dimples or creases) that causes it to produce multiple small jets. May be used against unarmored/lightly armored vehicles or as anti-personnel weapons.
- SIM-EFP: Simplified Improvised Multiple Explosively Formed Penetrator. Used at close range against armored vehicles, forgoes typical circular construction for emplacement in a long tube that increases chances of crew compartment casualties.
Cross Sectional Diagram of an EFP
mm = metal lining
oo = explosive
XX = copper
Typical employment for an an EFP IED is in an array of multiple units, sometimes as many as eight to ten together. Triggering is accomplished either through victim initiation (passive or active) or remote detonation and is dependent on the sophistication of the emplacer and their level of technical support. EFP arrays are typically arranged such that they detonate simultaneously and project in different directions to increase the likelihood of crew compartment casualites.
SIM-EFP emplacement can run parallel or perpendicular to the road depending on the objective of the emplacer. A single device or an array of them can be set up such that they disable a vehicle with other devices detonating later once crews have dismounted or begun attempting to retrieve the disabled vehicle. Certain countermeasures and techniques have been developed to significantly mitigate the EFP threat, however these require continual update and evolution as the threat situation changes.