An Israeli firm has devised a bolt-on reactive (exploding) armor panels for trucks, that will provide protection from EFP (Explosively Formed Projectiles). These are the precision weapons that have been coming from Iran. An EFP is a precision weapon, not an ad-hoc assemblage of explosives (like most roadside bombs). Your typical EFP is a cylindrical device, the optimal one often described as similar to a coffee can. But the cylinder metal must be thicker. You fill about 60 percent of the "coffee can" with explosives (C4, also known as plastique, will do). Then you insert a detonator on the closed end of the "coffee can" and a concave copper plug that is pushed into the plastic explosive. The tricky part here is that the depth of the concave copper part, and the thickness of the copper, have to be just right. It requires someone expert at math and the chemistry of explosives to make those calculations. You can make a mould for casting the copper plug, but you must make sure you get the thickness just so, or the weapon won't work.

You set the device off with the detonator, either via wire, or wireless, connection. When the C4 explodes, it forms the copper cap into a blob of molten metal, moving faster than a speeding bullet (about 1,500 meters a second). The blob stays intact, and lethal, for a few hundred meters, traveling pretty much in a straight line. But not straight enough to hit something more than fifty or so dozen meters away. The Israeli protection system uses the explosion of the reactive armor to break up the blob, making it largely ineffective against armor.

EFPs are difficult to aim. The user has to place it so that, when it goes off, it will hit a vehicle sitting in a position the user has already figured out. For this reason, EFPs are usually set up at places where vehicles have to stop. When the EFP hits an armored vehicle, it burns and punches its way through the armor. Once inside the vehicle, it injures or kills whoever it hits, as well igniting combustible material and generally scaring the hell out of everyone.

EFPs weigh under ten pounds, are small and easily carried and concealed. They are quick to set up. With all that, only about 600 have been used. Some appear to have been made in Iraqi workshops, in Shia parts of the country. But most others appear to come from Iran. Naturally, these "Iranian EFPs" don't have any distinguishing marks on them (indicating a state arms factory, or a "Made in Iran" label). The Iranians are not stupid, they don't want to admit supplying these weapons. But all indications are that, most EFPs are made in Iran. And their main purpose is to kill American and British troops, and cause more chaos in Iraq.