Homemade bombs built from pressure cookers, a version of which was used in the Boston Marathon bombings, have been a frequent weapon of militants in Afghanistan, India and Pakistan. Al-Qaida’s branch in Yemen once published an online manual on how to make one, urging “lone jihadis” to act on their own to carry out attacks.
President Barack Obama underlined Tuesday that investigators do not know if the twin bombing the day before that killed three people and wounded more than 170 was carried out by an international organization, a domestic group or a “malevolent individual.” There has been no claim of responsibility.
A person briefed on the investigation told The Associated Press that the explosives were fashioned out of pressure cookers and packed with shards of metal, nails and ball bearings to inflict maximum carnage.
The relative ease of constructing such bombs and the powerful punch they deliver has made them attractive to insurgents and Islamic extremists, particularly in South Asia. They have turned up in past bombing plots by Islamic extremists in the West, including a plan by a U.S. soldier to blow up a restaurant frequented by fellow soldiers outside Fort Hood, in Texas. One of the three devices used in the May 2010 Times Square attempted bombing was a pressure cooker, according to a joint FBI and Homeland Security intelligence report issued in July 2010.
Al-Qaida’s branch in Yemen gave a detailed description on how to make a pressure cooker bomb in the 2010 first issue of “Inspire,” its magazine that only appears online, in a chapter titled “Make a bomb in the kitchen of your mom.”
“The pressurized cooker is the most effective method” for making a simple bomb, the article said, describing how to fill the cooker with shrapnel and gunpowder and to create a detonator using the filament of a light bulb and a clock timer.
“Inspire” magazine has a running series of such training articles called “Open Source Jihad,” which the group calls a resource manual for individual extremists to carry out attacks against the enemies of jihad, including the U.S. and its allies. The magazine is targeted heavily at encouraging “lone wolf” jihadis.
An issue last year reprinted an older article by a veteran Syrian jihadi Abu Musab al-Souri addressing would-be jihadis proposing a long list of possible targets for attacks, among them “crowded sports arenas” and “annual social events.”