When Tamerlan and Dzhokhar Tsarnaev decided to build the bombs that ultimately killed three and injured hundreds at the Boston Marathon, they had to do little more than a quick Google search and a shopping run, highlighting the near impossibility of preventing improvised explosive devices from being used in the U.S.
The brothers used a step-by-step guide printed in Inspire, Al-Qaeda in the Arabian Peninsula’s magazine targeted at English-language speakers, according to law-enforcement officials. Issue 1, with the ominously titled section “Make a bomb in the kitchen of your mom,” is widely available on the Internet, hosted on dozens of servers in the U.S. and abroad — including the sites Cryptome.org and PublicIntelligence.net, the popular document-sharing service Scribd and the encyclopedic Archive.org.
The design itself is nothing new, published in the 1971 book The Anarchist Cookbook and the Army’s Improvised Munitions Handbook — the former has been available in most libraries for decades and the latter is freely available online. And the materials used — a pressure cooker, nails available in any hardware store, black powder from fireworks — are so ubiquitous that law enforcement can’t track them.
“You can buy pipes or pressure cookers anywhere,” said one federal law-enforcement official. “If you buy less than 50 lb. of black powder or fireworks, you don’t have to fill out paperwork. There are a lot of legitimate uses for these items and it’s impossible to monitor all of them.”
“Ninety-nine point nine percent of the people that are going to check that out or buy it are going to do it just because they are curious,” said Martin Reardon, vice president of the Soufan Group and a former chief of the FBI’s Terrorist Screening Operations Center. “They would never even consider making a weapon.”
The FBI and other law-enforcement agencies maintain a system of “trip wires” with businesses around the country designed to identify would-be bombers as they gather materials. After the 1995 Oklahoma City bombing, they identified fertilizer and diesel fuel for monitoring, adding chemicals like hydrogen peroxide, model-rocket engines and remote-controlled vehicles to the voluntary program. The effort is seen both as an enforcement tool and as a deterrent. Attempted Times Square bomber Faisal Shahzad, who received more-formal bombmaking training in Pakistan, built a larger and more complex explosive around a pressure-cooker bomb. But Shahzad told investigators after he was arrested that he used less powerful ingredients to avoid attracting law-enforcement attention. Tamerlan’s purchase of two “mortar” fireworks packages — which contain a relatively modest July 4 display of 48 shells — didn’t arouse suspicion. Law-enforcement officials found disassembled fireworks in a backpack allegedly belonging to Dzhokhar that was disposed of by his college friends.
Indeed as lawmakers in Washington have called for accountability after the Tsarnaevs slipped through the cracks, law enforcement and counterterrorism experts caution that IEDs of such simplicity may now be a fact of life in the U.S.
“You can’t shutdown the Internet, [and] no one wants to ban fireworks,” Reardon said. “It’s out there. The cat is out of the bag, and you can’t put it back in.”
Last week President Barack Obama issued a strong statement of support for the intelligence community, despite it having Tamerlan on their radar years before the attack.
“Based on what I’ve seen so far, the FBI performed its duties, the Department of Homeland Security did what it was supposed to be doing,” he said. Left unsaid was the growing belief that small-scale acts of terrorism are impossible to completely eliminate. “This is hard stuff,” Obama said. “One of the dangers that we now face are self-radicalized individuals who are already here in the United States — in some cases, may not be part of any kind of network … And those are in some ways more difficult to prevent.”
The American people appear to be internalizing that threat according to a TIME/CNN/ORC poll released last week. More than 60% of Americans believe terrorists will always find a way to carry out attacks, while just 32% — down from 40% two years ago — believe government can provide absolute security.
FBI officials wouldn’t comment on whether trip wires were in place at fireworks retailers in New Hampshire where Tamerlan purchased the fireworks because of the sensitivity of the matter.
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“With the advent of the Internet — and with all these materials being legal to purchase — someone who wants to do harm can buy one thing at one store, another ingredient at another, and there’d be no way of knowing what happened until after the attack unless someone raised concerns to law enforcement or there being some other intelligence,” the law-enforcement official said.
“They’re crude, they’re simple, and they’re effective,” Reardon said. “You can’t stop them all the time — the question is how you respond to the threat. Do you crack down like Big Brother, or do you try to allow people to live their lives as normally as possible?”