But the armor on those vehicles cannot stop the newest bomb to emerge, known as an explosively formed penetrator (EFP). The Pentagon plans to replace virtually all Humvees with MRAPs to provide better protection against roadside bombs, responsible for most casualties in Iraq.
The document, dated Jan. 13, is called an urgent universal need statement. The statements are written by field commanders in all services, who want commercially available solutions to battlefield problems.
Since MRAPs are so much safer against traditional roadside bombs, the document says, Iraqi insurgents' use of EFPs "can be expected to increase significantly."
As a result, the Marine commanders in Iraq who wrote the statement asked for more armor to be added to the new vehicles.
Armor performance information is pretty sensitive even when it is not classified, so I have waited until enough details surface in public before broaching the issue. This shouldn't come as much of a surprise consider that an EFP managed to penetrate the thick skin of a British Challenger 2 tank. If an EFP can go through a 60-ton tank encased in Chobham armor, what are the chances that the 15-ton MRAP's rolled steel would perform any better?
The MRAP's V-shaped hull design is really meant to deflect the energy of an explosion and not the EFP's focused blast. With enough armor, the hull curvature might deflect them in some situations, but the Marines shouldn't get their hopes up because EFPs have been known to resist even reactive armor.
I'm still not willing to dismiss the MRAP entirely because forcing the insurgents to use more EFPs could reduce causalities. Imagine that you are trying to pierce a 2-liter bottle of soda locked in a refrigerator and the only tools available were a ballista and a 18th Century cannon. The ballista's arrow would probably have enough force to go all the way through the fridge, but its damage would be highly localized. Heck, you might even miss the two-liter entirely.
Using the cannon is a different story. A cannonball might not pierce the fridge, but it would implode (or "spall") the fridge door, potentially destroying everything inside. Adding armor to the fridge would help you resist the cannonball's more distributed impact, but it would provide less protection against the ballista's bolt.
This may play out in Iraq in the same way. An EFP may injure one or even two passengers in an MRAP, but the rest of the crew would be relatively safe. Its not a perfect solution, but then again, are there any perfect solutions in war?