Evolution of Terrorist IEDs vs US Countermeasures

Excerpts from an excellent article on Wired.com on the arms race/evolution between terrorist IEDs and US military countermeasures/defenses.

U.S. Military Learns to Fight Deadliest Weapons

Jieddo was formally signed into existence by the Department of Defense just four years ago, in February 2006. But it has its origins in a personal request written by the chief of US Central Command, John Abizaid, to his superiors at the Pentagon in mid-2004. As the number of casualties caused by IEDs in Iraq mushroomed, he insisted that the only solution was a “Manhattan Project-like” marshaling of scientific and military resources. Since then, Jieddo has gathered a staff of more than 3,600 government employees and contractors, established projects with all four military services and every intelligence agency, and spent more than $17 billion.

In Iraq, Jieddo has succeeded in drastically reducing the carnage caused by IEDs. At the start of the war in 2003, every device that troops encountered resulted in, on average, the injury or death of at least one member of the coalition forces; by 2009, insurgents had to put down nine IEDs to cause a single casualty. But even as the number of attacks on coalition forces in Iraq dwindles, IEDs remain the principal killer of US troops in combat. In Afghanistan — where the number of IED incidents doubled in 2009 and caused 75 percent of casualties in some areas — Jieddo faces a new generation of more ingenious, and bigger, bombs.

It wasn’t until the summer of 2004 that Iraqi bombsmiths reached into the high end with the explosively formed penetrator, or EFP. Using technology developed during World War II, today’s EFPs are made from a short length of steel or PVC pipe packed with explosives, sealed and capped with a concave copper disk. When the explosives detonate, the blast energy inverts the copper plate into a ragged slug traveling more than a mile per second and capable of punching through tank armor 300 feet away. Iranians used EFPs during their eight-year war with Saddam Hussein and later supplied the technology to Hezbollah guerrillas in Lebanon. Bomb-builders there added passive infrared triggers, sensors that detect motion by responding to changes in temperature — like that created by the engine of a passing truck. Because they don’t use radio frequencies as triggers, they’re invulnerable to electronic jamming.

In Iraq, the effectiveness and frequency of EFP attacks soon proved so devastating that individual soldiers began improvising their own countermeasures. One simply bought a toaster in a bazaar and hung it from a pole welded to the front of his Humvee — a heat decoy. According to The Washington Post, this and similar ideas led, in May 2006, to one of Jieddo’s first innovations: the Rhino. The Rhino used a glow plug — an electric heating element for warming diesel engines before ignition — housed in a steel box on the end of a 10-foot boom. It worked so well that it could not only trigger an EFP and take the impact of the high-velocity metal slug but, on at least one occasion, continue working afterward.

It took only six weeks for the insurgents to respond. They adjusted the firing angle of their EFPs so that the slug struck 10 feet behind the decoy. Jieddo countered with the Rhino II, fitted on an adjustable-length boom. Along with electronic jammers, the Rhino II became standard on US vehicles in Iraq. More than 16,000 of the gadgets had been deployed to the Army and Marines by the end of 2008.

But at the beginning of this year, US forces in Iraq reported a new version of the passive infrared trigger, nicknamed the Black Cat. It looked exactly like a regular passive infrared sensor, but the motion detector was altered to be triggered instead by radio frequencies. Shielded to prevent it from being set off by household radios and with reduced reception range, the new device is one of the most devious yet. Designed to detect the passing bubble of a coalition jamming system’s powerful radio field, the Black Cat has brought Jieddo full circle: It is an IED that will detonate only when it detects an IED countermeasure.

All bombmakers leave a technical signature in their devices — whether it’s a pattern of hot-gluing wires to a circuit board or the repeated use of a favored component. One Afghan IED builder has been linked to at least 90 separate pressure-plate triggers made from plywood and the four heavy springs from old-fashioned bicycle seats. Every one of his triggers has five separate mechanical characteristics in common. And there is biometric evidence, too: “When he wound the wires together to attach them to the springs for the contact, he left his DNA behind,” Wickham says.

The weapons technical intelligence process has also revealed a broader scheme at work. The tactics of today’s insurgent bombmakers are the product of a long-simmering melting pot of global terrorism: expertise developed by the IRA and disseminated in a clandestine exchange of bombmaking wisdom that included members of the Spanish separatist group ETA and the FARC guerrillas in Colombia. In Iraq, Wickham recognized techniques he’d seen in Northern Ireland 30 years ago. “I can take you to Baghdad and show you a command wire set up in October ‘07,” he says. “I can take you to South Armagh and show you exactly the same tactical design from 1980.” US military intelligence analysts already suspect that the lessons learned by IED cells in Baghdad are being put into practice by the Taliban. “If it works in Iraq long enough,” one analyst says, “they’ll start moving it into Afghanistan.”

Afghan bombmakers, faced with the sophistication of US countermeasures developed in Iraq, have begun moving backward down the continuum represented by Mark Maginess’ graph. After their radio-control bombs were smothered by jammers, the Taliban turned not only to “command wire” — physical connections between trigger and bomb — but also to the even more reliable “command pull,” a simple switch attached to monofilament fishing line or even a piece of string. With these, at least, the triggerman must remain nearby for the attack and is therefore relatively easy to catch or kill. But almost all of the devices encountered during 2009 by Jieddo’s Afghan operation, Task Force Paladin, were simpler still and harder to locate: large bombs triggered by pressure plates buried in the middle of dirt roads. “You drive over it, your weight initiates the pressure plate — blows up under your belly where it’s most effective,” says Jeffrey Jarkowsky, Paladin commander until late last year.

These rudimentary mines can sit for days or even months waiting for a victim. They’re often made from whatever is at hand in a rural environment, like the bicycle seat springs or two carpentry saw blades tensioned into a bow — anything that lets two contact surfaces meet to complete a circuit. More recently, the pressure plates have been built with less and less metal. One type of device uses only two strips of aluminum tape; another, single strands of wire and contacts made from fragments of the graphite core from a C-cell battery. As a result, the metal detectors used by US route-clearance teams are becoming ineffective.

And since the stocks of military ordnance left over from the Soviet war have been depleted, three-quarters of Afghan IEDs have been made not with pilfered artillery rounds but with more common agricultural ingredients like ammonium nitrate fertilizer. Packed into 5-gallon plastic containers and buried in a dirt road, these charges are utterly invisible to metal detectors. Task Force Paladin is using ground-penetrating radar to find them, but that works only from right on top of a bomb, increasing the risk of setting it off. And many chemical sniffers deployed in Iraq detect only the molecules produced by decaying TNT — not ammonium nitrate. Jieddo scientists have been working for four years on a means of detecting homemade explosives at a distance; a solution has so far eluded them. They have also been trying to figure out how to detect the electrical blasting caps used to detonate many types of IEDs, so they can be set off from a safe distance.

Perhaps inevitably, some of the best means of beating the Afghan bombers have proved to be the simplest: Many vehicles are now protected by front-mounted rollers that trigger mines ahead of a convoy. If in doubt, troops are trained to simply get out and look for clues like disturbed ground or a pile of trash that wasn’t there the day before. “Even today, with all the technology,” says Jarkowsky, “the best detector of an IED is the human eye.”

Late one afternoon in April, Llamas shows me the latest device they’ve been working on, just in from Afghanistan. A neatly made plywood box about 8 inches high and 5 inches square, it has a length of replica detonation cord emerging from the base. Llamas pulls the box open, revealing a layer of soft foam and a wooden plunger attached to the lid. When stepped on or driven over, he says, the foam is compressed and the tip of the plunger, which is saturated with a chemical, descends into a chamber at the bottom of the box. That chamber contains a second substance, and when the two chemicals mix, a pyrotechnic reaction ignites the end of the detonation cord, which leads to an explosive charge.

The box is the logical conclusion of years of reverse evolution in insurgent weapons technology. Without a power source, a blasting cap, or a single piece of wire or metal contact, it has no electromagnetic or metallic signature. Linked to a charge mixed up from odorless homemade explosives, packed beneath a dirt road, it would be all but impossible to detect: a Flintstones land mine. “It’s a block of wood, basically,” Llamas says.

And although the wooden IED was found and photographed in Afghanistan and has been carefully reconstructed thousands of miles away here in the Mojave Desert, the Taliban insurgents apparently remain one step ahead of technicians here. The pyrotechnic chemical mix remains a mystery.

“We don’t know what it is yet,” Llamas says. “We’re still trying to figure that out.”

Adam Higginbotham

See also related at US Signal Jammers vs Remotely Detonated IEDs.

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