Bruce Hoffman, professor of security studies, on the techniques used by al-Qaida operatives:

"The explosives element, the training and the backpacks -- all are part of the core al-Qaida bomb-making curriculum as we've seen in two specific incidents in the United Kingdom, and if you take out the backpacks, the last three significant U.K. incidents."

U.S. Resident Held Without Bail in Terrorism Case

September 22, 2009, The Washington Post