Steven Cherry: The weapons that wreaked havoc at the Boston Marathon this month, killing three and maiming scores more, were improvised explosive devices, or IEDs. As it happens, the U.S. Army has a lot of experience with IEDs—a lot of unhappy experience. In an article about them in 2008, my colleague Glenn Zorpette wrote, “IEDs have killed untold thousands” in our two recent wars, and he cited figures that “nearly half of all combat fatalities in Iraq and roughly 30 percent of those in Afghanistan were due to IEDs.”
He also wrote—and this was as of 2008: “The U.S. military has responded with the most intensive program of technology development in at least a decade. It has spent [US] $12.4 billion over the past three years on counter-IED equipment, technology R&D, training, and other measures through the Joint IED Defeat Organization and its predecessors.”
My guest today is Barry Shoop. He’s a colonel in the Signal Corps and a professor and deputy head of the electrical engineering department at the U.S. Military Academy at West Point. His own Ph.D. in electrical engineering is from Stanford University, and he’s also a graduate of the U.S. Naval War College. He’s a Fellow of the SPIE and a Fellow of the IEEE. Most importantly, for our purposes, in 2006 and 2007 he served as chief scientist of the Army’s Joint IED Defeat Organization [JIEDDO]. He joins us by phone.
Barry Shoop: Thank you.
Steven Cherry: According to public reports, the bombs in Boston were constructed out of pressure cookers and used nails and ball bearings to carry the force of their explosions. How much were they like or unlike the IEDs the Army saw in Iraq and Afghanistan?
Barry Shoop: These were fairly rudimentary compared to some of them that we saw in both Iraq and Afghanistan. Fundamentally, the explosive that was reported to have been used is gunpowder, which is a low explosive. You compare explosive materials that detonate, which means they explode faster than the speed of sound, those are high explosives, compared to materials that deflagrate, which are low explosives. And low explosives are used in things like gunpowder, pyrotechnics, flares, fireworks. So the explosive that was used, being gunpowder, was fairly low explosive. The container, being a pressure cooker, was used to house and contain that, and then it was reinforced again by records, ball bearings, things like nails, to increase the lethality of the explosion.
Steven Cherry: So I gather that besides the actual explosive used, the main difference between a crude and a sophisticated IED would be remote detonation?
Barry Shoop: In some cases. I mean, when you look at a general taxonomy of an IED, it fundamentally can be broken down into roughly five components: You have to have some kind of a power source, generally a battery; some kind of arming and possibly a firing device or firing switch; you have an initiator or main charge, which is the explosive; and the container.
And the level of sophistication runs from the type of charge that’s used, either low explosive or high explosive. Many of the kinds of charges that we found in Iraq particularly were military ordinance that were left over from many wars past, and so they were high explosive. And then you run the gamut of things, like the arming and firing switches predominantly are at the level of sophistication, although we did see in Iraq cases where an individual charge, even though it was a military charge, was insufficient to penetrate armor. And so we saw things like explosively formed penetrators being used, which raised the sophistication of the charge itself.
But the firing switch or arming device runs the gamut of sophistication, all the way from very, very crude individual command wire detonation, where somebody has to sit at the end of the command wire and detonate it, to early on in Iraq, we saw initiators that were key fobs that you would find in a car to open your car door that had very short range, progressing to long-range cellular phones, even to cellphones and pressure plates and other kinds of switches.
Steven Cherry: Yeah, there were reports that law enforcement in Boston had shut down the cellular networks in and around Copley Square so that no further bombs could be detonated. That turned out not to be true, and there are all sorts of reasons why they wouldn’t do that. Would that have been effective?
Barry Shoop: It could have been effective if you knew—the challenge that you have is knowing exactly what the trigger mechanism is, and if you know for sure that the trigger mechanism is a cellular telephone, there are techniques. You could, in fact, shut down the cellular networks so that no telephone signals could get through.
But that requires knowledge a priori that you are, in fact, dealing with a cellular telephone, and the other part of this is that the trigger mechanism really depends on the environment—the friendly capability as well as the enemy capability. So if you have a particularly robust countermeasure and the enemy recognizes it, then alternative trigger mechanisms are chosen. And that’s kind of one of the things that we found from a military perspective in both Iraq and Afghanistan, and others have found it around the world: Go to Britain with Northern Ireland, you go to Israel with Lebanon and Palestine.
What happens in our case with Iraq was U.S. jamming capability became fairly effective, and as a result, the enemy moved away from radio and cellular triggers back to more rudimentary command wire and pressure plates, which were less sophisticated but much more robust against jamming.
Steven Cherry: Jamming would be a lot more practical in a war zone than the downtown of a major city. What are some of the other problems that law enforcement faces in a place like Boston?
Barry Shoop: In an environment like Boston, as you said, jammers are particularly aggressive, if you will. They not only jam the local environment for the IED, but they jam everything in the area—consumer electronics, cellphones, and everything else like that. So jammers themselves, large-scale jammers like we’ve seen in Iraq and Afghanistan, where you are traveling down a road.
Now, there are smaller-scale jammers that can be used if you identify the IED ahead of time. So if you knew that there was an IED in a local area, law-enforcement officials and first responders can, in fact, use smaller-scale jammers, which just jam a very small local area around the IED itself to prevent detonation. Now, that, again, presupposes that you know the IED has some sophisticated electronics in it, perhaps cellphone triggering or those kinds of things.
Steven Cherry: So, broadly speaking, where are we at with IEDs? How effective was the Army by the end in Iraq, for example?
Barry Shoop: So, what I would tell you is that we have, over the years, made some significant progress, but there remain many, many challenges. Detection continues to remain a significant challenge. From detection, or if you think about it, from a sensing perspective, the challenge is really a series of weak component signatures in an incredibly complex background environment. Now, that goes for both a war zone as well as an area like Boston.
There’s a wide variety of types of devices, some containing large quantities of metal, while others very little. Some have significant electronics associated with the arming or triggering mechanism, while others have none. Some have large quantities of explosive material, while others have very little. And then the environment serves to mask these particularly weak signatures, clutter from the natural man-made environments, atmospheric obscuration, dense electromagnetic spectrum, man-made and urban and rural environments. All of those things make sensing and detecting these devices particularly challenging.
Once you know that there is a device there, then you can apply resources to either reduce the potential for a detonation or reduce the impact of the detonation itself. Special problems outside the war zones, like we talked about jammers, are a standard approach to disrupting the electronics associated with an IED if we know there’s electronics. But in an urban environment, you really can’t use that effectively when you don’t know where the device is.
Steven Cherry: We haven’t had many IED attacks in North America, but in that 2008 article, we wrote that IEDs were “the weapon of choice for the world’s terrorists, insurgents, militias, guerrillas, revolutionaries, and marginal or failed states.” Is the U.S. likely to see more of them on its home soil, in your opinion?
Barry Shoop: I think so. I said in that article that Glenn Zorpette wrote in 2008 that we really need to, as a military and as a country, figure out how to deal with these problems. Because if we don’t figure out how to deal with them outside the U.S., we’re going to see an increased effort inside the U.S. What I would tell you is that around the world right now, there’s probably on the order of between 400 and 500 events each month considered to be IED events outside of Afghanistan. And you can characterize them in a wide range of different applications. There are conflicts going on, as we know, in Afghanistan and Iraq, but Sudan, Somalia, Israel, Lebanon, Palestine. Drug cartel use in Mexico, Colombia, and Peru. There are insurgencies going on in Chechnya, Russia, Nigeria, Northern Ireland.
And as you said, there’s really a threat continuum, if you think about it, that has adopted and used IEDs, and that threat continuum begins with the disenfranchised and moves on to smugglers, criminals, pirates, narcotics traffickers, insurgents, and at the extreme end are terrorists. We’ve seen quite a number, not huge numbers, but we have seen numbers here in the United States in the past going back to 1995, the Oklahoma City bombing, 1996 at the Olympic games, and even in 2010 in Times Square, we saw a vehicle bomb that included a pressure cooker that included 120 firecrackers in it, which are low explosives.
Steven Cherry: So, broadly speaking, are you optimistic that we will be able to counter them better and better? Or are you more pessimistic that IEDs are just going to become an ever-growing problem?
Barry Shoop: I have to be optimistic, otherwise I’ll be too depressed. But really, there are technological solutions, and there are other social solutions to this, and obviously dealing with IEEE and IEEE Spectrum, most of the audience is interested in technological solutions to it.
But as I said, the detection problem is a particularly challenging problem. It has driven technology improvement since we have begun looking for these kinds of devices. We have vastly improved the armoring capability that we have, particularly for military systems, but that can span not just military, but can move into law-enforcement kind of systems.
But the really, in my mind, promising area of this effort is in almost a network science approach to things. If you can understand the network and you can understand human—you can’t always understand human nature, but you can understand what motivates people to do the kinds of things that they do—and you can get inside of the telephone network, you can get inside the social network, you can begin figuring out these, either the drug networks or the terrorist networks, you can begin linking technology with the human dimension. And I’m optimistic that we are making strides in those areas to be able to predict and detect and ultimately prevent these.
Steven Cherry: So it sounds like, just to make a comparison, the most successful hacking is often because of its social engineering aspect. And it sounds to me like you’re saying some of the most effective countering of IEDs is social engineering, in effect, as well.
Barry Shoop: If we can get inside that network, it’s much easier than trying to find an individual device sitting beside a road or sitting in a very dense crowd. And so if we know that it’s coming and we can predict it, we have much higher percentage of probability of preventing.
Steven Cherry: IEDs are the ultimate asymmetric attack right? We spent billions of dollars trying to counter them, and these guys in Boston maybe spent a hundred bucks. The world was appalled by what happened in Boston, but it must have had an added element of frustration for you.
Barry Shoop: Absolutely. When you see these kinds of things, and the human dimension, and the consequence for humans, it’s just gut wrenching. And it’s been that way ever since I was the chief scientist and advisor to the director at JIEDDO. We saw on a regular basis what was going on, and we were attempting to find technological or other solutions to try to prevent the human carnage, and we continue to work that.
Steven Cherry: Barry, it’s a Sisyphean effort, but as Glenn also wrote, “the alternative scenario is not pretty.” Thank you for you lifelong service, your work with the Joint IED Defeat Organization, and for joining us today.
Barry Shoop: Thank you very much.
Steven Cherry: We’ve been speaking with Col. Barry Shoop of West Point about the difficulty of countering the threat of improvised explosive devices.
For IEEE Spectrum’s “Techwise Conversations,” I’m Steven Cherry.
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