In it, but not of it. TPM DC
"It's sort of one puzzle piece. ... It's a puzzle piece that tells you a little bit, but in this case, it doesn't tell you a whole lot," said Brian Jackson, safety and justice program director at RAND, whose terrorism research largely focuses on terrorist's organization learning and adoption of new technologies.
Pressure cooker bombs have been associated with Islamic terrorists for almost a decade now. Bombs require a vessel that holds explosive material and can withstand the pressure that builds up prior to detonation. Pressure cookers are ideally suited to this purpose. In 2004, the Department of Homeland Security issued an internal memo on "potential terrorist use of pressure cookers" that said the making of pressure cooker bombs was "commonly taught in Afghan terrorist training camps."
Six years later, in the summer of 2010, instructions for building pressure cooker bombs appeared in the inaugural issue of "Inspire," a jihad-themed magazine linked to the late Al Qaeda cleric Anwar al-Awlaki. The article, which was entitled "Make A Bomb In The Kitchen Of Your Mom," touted using household ingredients as a way to make explosives with "readily available ingredients" and without raising "suspicion." The use of pressure cookers was identified as the "most effective method" for making a bomb out of household materials in the "Inspire" article. That same month, the Department of Homeland Security issued another warning that improvised explosive devices made with pressure cookers "frequently have been used in Afghanistan, India, Nepal, and Pakistan."
However, Jackson said the fact Al Qaeda published instructions for making pressure cooker bombs could have led other, unrelated terrorists to adopt the technology.
"A lot of this information is out there for better or for worse," said Jackson of the bombmaking manual in "Inspire." "Whether or not it was somebody inspired by Al Qaeda, one of the things that magazine did by being English-language and trying to get information out there is sort of disseminate this stuff."
Jackson argued other terrorists would appreciate pressure cooker bombs for the same reasons as Al Qaeda.
"The bottom line is that terrorists are building improvised explosive devices, most of them are not highly skilled individuals," explained Jackson. "So, a vessel like this where they can buy something off the shelf and not have to know how to machine something and produce a vessel that will work well is attractive to them."
Jackson also said information about bomb components is more useful in identifying terrorists behind multiple attacks than it is in isolated incidents like the Boston bombing.
"Where there's information content in details like this are often more in cases where you have bombmakers who are making a lot of bombs," Jackson said. "When they're one-off incidents like this, you know, at least so far, fortunately, it's sort of one puzzle piece. And it's a puzzle piece that, because pressure cookers are something that is easy to get, it's a puzzle piece that tells you a little bit, but, in this case, it doesn't tell you a whole lot."