Carnage at Boston Marathon (15 April 2013). |
The two
used in Monday’s attack are similar to devices in the failed 2010 Times Square
bombing and the 2006 Mumbai train bombings that killed more than 200 people,
officials said.
“They’re
made out of stainless steel and the whole idea is the pressure builds up and
when it explodes it rips the metal into shrapnel . . . And it all fits in a
duffle bag,” said Matthew Horace, retired special agent in charge of the
federal Bureau of Alcohol, Tobacco, Firearms and Explosives field office in
Newark.
Pressure cookers have become terrorists’ bomb casing of
choice because security teams usually remove garbage cans and mailboxes in
advance of high-profile or sensitive events, Horace added.
A typical pressure-cooker. |
Pressure cookers are common in South Asia and the Middle
East and don’t usually arouse suspicion there, according to an Interagency
Counter Terrorism Task Force advisory sent out to NYPD and other
first-responders yesterday.
But because the cooking appliances are less common in the
United States, “the presence of a pressure cooker in an unusual location such
as a building lobby or busy street corner should be treated as suspicious,” the
advisory said.
When American citizen Faisal Shahzad tried to blow up
Times Square with a SUV-load of explosives in 2010, he used a pressure-cooker
bomb packed with 120 firecrackers as part of the payload.
Authorities also found two pressure cookers — along with
other bomb-making materials — in the Texas hotel room of Naser Jason Abdo, an
Army private arrested in 2011 for allegedly plotting to blow up a restaurant full
of GIs.
The inexpensive bomb casings are used with greater
frequency outside the United States, especially in Pakistan, Afghanistan and
India.
To build a pressure-cooker bomb, terrorists surround an
explosive with metal objects such as nuts and bolts or nails — to act as
shrapnel — and use a cellphone, digital watch or garage-door opener to detonate
the device.
Pressure-cooker packed with explosives, nails, and ball-bearing balls. |
Pressure cookers were regularly used in Afghanistan to
attack US and coalition forces.
Al Qaeda’s Yemen branch provided detailed descriptions of
how to build a pressure-cooker bomb in a 2010 issue of its magazine “Inspire,”
in an article titled, “Make a bomb in the kitchen of your mom.”
White supremacists also have circulated copies of the al
Qaeda magazine on their Web forums, according to the SITE Monitoring Service, a
US independent group tracking online militant messaging.