Security nudges bomb makers to weaker bombs

An ever-widening crackdown on bomb-making materials has forced amateur terrorists to rely increasingly on less powerful homemade devices.

But with bomb-making recipes a mouse-click away on the internet, experts said devices like the one that injured 29 in New York City's Chelsea neighborhood on Saturday are easier to make than ever before and will likely remain an ongoing threat.

“If you’re using pressure cookers, you’re defaulting to readily available, commercially procurable materials," said Bruce Hoffman, director of the Center for Security Studies at Georgetown University. "But the simplicity, in some respects, is in its sophistication. It may be simple but it’s now become a tactic and a weapon that’s available on a much broader scale because of the internet, social media, than ever before.”

Authorities said the device that exploded in Manhattan was contained in a pressure cooker and contained residue of Tannerite, a legal product used primarily for target practice. The bombs planted at the Boston Marathon in 2013 used gun powder extracted from fireworks.

A bomb also exploded this weekend at a charity race in Seaside Park, New Jersey, and another device was exploded early Monday by authorities at a train station in Elizabeth, NJ.

The homemade bomb that Oklahoma City bomber Timothy McVeigh used to kill 168 people in 1995 had a mix of nitromethane fuel used in drag racing and ammonium nitrate fertilizer. But while McVeigh got bomb-making instructions from a $12 how-to manual, the digital age has made it even easier. The Tsarnaev brothers, for example, learned how to build the marathon devices from Inspire Magazine in an article titled "How To Build a Bomb in Your Mom's Kitchen."

“It used to be there were manuals that people could get their hands on to do this,” said Victor Asal, a political science professor and terrorism expert at the Rockefeller College of Public Affairs and Policy at the State University of New York at Albany. “These days you go to the web, you look in the right forum and you’re likely to find sources on how to make these sort of bombs. So it’s not a surprise that somebody could do this.”

Federal authorities have fought back. Last month, the U.S. Department of Homeland Security commissioned the National Academies of Sciences, Engineering and Medicine to study ways to limit access to bomb-making materials like ammonium nitrate.

Increased surveillance since the Sept. 11, 2001, terror attacks has also made access to those materials more difficult, forcing would-be terrorists into using less powerful explosives, said Hoffman, the Georgetown University professor.

“They’re less powerful than ammonium nitrate," he said. "Ammonium nitrate is even less powerful than, let’s say, commercially available TNT or plastic explosives. So, there’s like an inevitable grounds race on this very ground-level, unsophisticated dimension. But the bombs are less powerful and less destructive. So, it’s not a complete zero-sum game. But of course, people who are determined to use these weapons always find a way to do so.”

“The point is terrorism is a fact life these days, like car crashes, like street crime," Hoffman said. "It’s just another challenge that we live with in society, but we shouldn’t allow it to rule our lives and determine our daily activities.”

Brian Nussbaum, a professor in the College of Emergency Preparedness, Homeland Security and Cybersecurity at SUNY Albany, agreed.

"The details of the device used in New York are not yet clear, but the general project of creating an explosive device out of a pressure cooker isn't very complicated,” Nussbaum said. “We've seen such devices used in plots and attacks on the homeland, as well as abroad.  In fact, Al Qaeda in the Arabian Peninsula included information on how to produce such a device in their English language publication, Inspire Magazine."

"These directions were in the Open Source Jihad section of the magazine, and thus are widely available online," he added.