Late in the evening of Saturday, Sept. 17, New York City residents living in Manhattan’s Chelsea district received some unsettling news via their cellphones. After hearing an emergency alert, they were informed that there had been a bomb blast in their neighborhood, and that they should stay inside and away from their windows until further notice.
An attack based on an Improvised Explosive Device, or IED—a hallmark of the wars in Iraq and Afghanistan—had once again wreaked havoc in a major U.S. city. The Chelsea explosion, which injured 29 people, was one of a series of attacks and related events that ended with the arrest of a 28-year-old suspect in Linden, New Jersey on Monday morning. The events began with a pipe-bomb explosion near the seashore in New Jersey, on Saturday morning, and continued on Saturday night with the Chelsea bombing, on West 23rd Street in Manhattan and the discovery of another bomb near the Chelsea site. On Sunday night, five other bombs were found in a backpack in Elizabeth, New Jersey. All of the bombs are believed to be the work of a single person.
For Col. Barry Shoop, head of the Department of Electrical Engineering and Computer Science at the U.S. Military Academy at West Point, the attacks were a grim confirmation of a long-held belief. “If we can’t solve this problem outside of the United States, we are going to see them [IEDs] inside the borders of the United States,” he said in an interview shortly after the arrest of the suspect. In a podcast interview with IEEE Spectrum in 2013, after an IED killed 3 and wounded 264 in Boston, Shoop pointed out that every month there were 400 to 500 IED “events” around the world, not including Afghanistan. (Shoop is also the current president of the IEEE.)
In 2006 and 2007, when IED attacks were taking a heavy toll during the Iraq war, Shoop was chief scientist of the Pentagon’s Joint IED Defeat Organization (JIEDDO), which sought to apply technology to reduce their murderous efficacy. When he was at JIEDDO, Shoop used a graphic “that showed how long it took IED builders to get to a sophisticated level.” In Northern Ireland, where IEDs were used extensively in the 1970s, “it was in years,” Shoop says. “But in Iraq and Afghanistan it was months, because of all the instruction on the Internet.”
That easy availability of bomb-making information is believed to be a factor in the New York and New Jersey events. Authorities have noted that in the Chelsea incidents, the bomb that exploded and the one found unexploded nearby were both pressure-cooker devices, quite similar to the IED used in the Boston Marathon attack in 2013. Manuals for building pressure-cooker bombs have appeared on websites associated with many extremist groups, including ISIS and Al Qaeda. The devices are little more than an ordinary pressure cooker packed with explosives and shrapnel, such as metal screws, and a means of detonating the device remotely. Typical remote detonators are cellphones, garage-door openers, or simply a long pair of twisted wires.
JIEDDO (which is now called the Joint Improvised-Threat Defeat Agency) came up with many different countermeasures for IEDs, and put some of them into the streets of Iraq and Afghanistan. Among its more successful creations were radio-jamming systems to disrupt the cellphone signals that were used, early on, to trigger IEDs; surveillance systems to hunt for signs that an IED had been emplaced in a street, field, or building; and heavy vehicles specially designed to deflect the blast from an IED. Such countermeasures are credited with cutting losses caused by IEDs to less than half of what they would have been.
But in the urban environment of a city in a developed nation, many of the military countermeasures are unusable, Shoop says. “Obviously, we’re not going to build high-power jammers and drive down city streets and turn off everybody’s cell phones, televisions, and radios,” he notes. Still, he believes that some of JIEDDO’s breakthroughs could be adapted for urban use. For example, JIEDDO had some success by monitoring areas believed to be at risk from many different angles, at all times of the day and night, and even in different frequency bands—visible light, infrared, and so on. The data collected was sometimes analyzed by sophisticated programs, which looked for signs of something amiss.
Shoop suggests such a system could some day help detect urban IEDs. It would make use of surveillance cameras already installed in many cities, and augment them with other sensors, for example ones capable of detecting the chemical or gas signatures of explosives. Internet-of-things modules would enable it to feed its data into databases scrutinized by sophisticated, AI-based software. “Persistent surveillance in an IoT configuration is probably where we are headed,” Shoop says.