Paris explosives are a key clue to plot

Story highlights

  • Peter Bergen: Terrorists used an unstable compound made from household ingredients
  • He says authorities in the United States and other Western countries need to be on the lookout for bulk purchases

Peter Bergen is CNN's national security analyst, a vice president at New America and a professor of practice at Arizona State University. He is the author of "Manhunt: The Ten-Year Search for bin Laden -- From 9/11 to Abbottabad."

(CNN)French prosecutors say the bombs used in the terrorist attacks in Paris on Friday were made from TATP, a fact that yields important clues about the way the plot was planned and executed.

TATP-based bombs are built using the common household ingredient hydrogen peroxide, which is used to bleach hair. Such bombs have been a signature of jihadist terrorists in the West for more than a decade because the materials are so easy to acquire, unlike military-grade explosives, which are tightly controlled in much of the West.
Their use in the Paris attacks, as well as in terrorist plots in London and in the United States over the past decade, should remind law enforcement in the West that these TATP bombs are what jihadist terrorists may deploy in the future.
    What is tricky about TATP bombs is that they are quite difficult to make because their ingredients, when combined, are highly unstable and can explode easily if mishandled. To make an effective TATP bomb requires real training, which suggests a relatively skilled bomb-maker was involved in the Paris plot, since the terrorists detonated several bombs.
    It also suggests that there was some kind of bomb factory that, as yet, appears to be undiscovered, because putting together such bombs requires some kind of dedicated space. And it also suggests that there were probably tests of the bombs in an isolated place to ensure that they worked.
    The dangers of TATP bombs can be seen in the case of Matthew Rugo and Curtis Jetton, 21-year-old roommates in Texas City, Texas. They didn't have any bomb-making training and were manufacturing explosives in 2006 from concentrated bleach when their concoction blew up, killing Rugo and injuring Jetton. The pair had no political motives: They had just wanted to blow up vehicles for fun.
    Others in the United States have built TATP bombs with far more malevolent intent. Najibullah Zazi, who grew up in New York City, wanted to blow up as many commuters as possible on the Manhattan subway system.
    Zazi was trained by al Qaeda to make a TATP bomb in Pakistan, and during the summer of 2009, he made bulk purchases of hair bleach in suburban Denver and set up his bomb factory in a nearby motel room.
    He mixed and cooked batches of hair bleach in the kitchenette of the motel. On the night of September 6, 2009, as he labored over the stove, Zazi sent several emails to an al Qaeda operative "Ahmad." The emails contained a well-