Type of bombs used in Brussels by Islamic State likely been seen before

By THOMAS GIBBONS-NEFF | The Washington Post | Published: March 23, 2016

WASHINGTON — In the hours after the blasts that killed at least 31 people in Brussels Tuesday, investigators began piecing together how the Islamic State managed to detonate three bombs in the span of roughly an hour across the city. One question is how the individuals managed to build the devices and if they would resemble or possibly even match the bombs used during the Paris attacks last fall.

News reports in the aftermath of the attacks suggested that the terrorists used bombs made primarily of a peroxide-based explosive, triacetone triperoxide, known as TATP. It is unclear if the attackers used small arms prior to detonating their bombs, however if they used TATP-based explosives it would be one more example of their continued use in terrorist attacks across Europe.

Highly unstable, peroxide-based explosives such as TATP and its sibling hexamethylene triperoxide diamine or HMTD, have been used in terrorist bombs for decades. TATP first gained notoriety after the Sept. 11, 2001, attacks when Richard Reid, known as the shoe bomber, unsuccessfully tried to detonate a TATP-triggered explosive during a Paris to Miami flight in December 2001. TATP was also used in the 2005 London bombings that killed 56 as well as in the November 2015 attacks in Paris.

TATP's ingredients, such as concentrated hydrogen peroxide and acetone, are extremely easy to procure and cook into an explosive. But the powdery substance is highly volatile and potent, earning it the nickname "The Mother of Satan." A few grams of TATP can easily blow off fingers, while concentrated pounds of it are devastating.

According to an Army explosive ordnance disposal technician, who requested his name be withheld because of his current employment, TATP-based explosive devices are rarely seen in war zones such as Iraq and Afghanistan because of how temperamental the material is and stable, military-grade explosives are readily available. TATP, he said, has become a staple in Europe because of its accessible ingredients and how they raise little suspicion when purchased individually.

According to Brian Castner, a former Air Force explosive ordnance disposal technician and author of the book "All the Ways We Kill and Die," the use of TATP-based explosives in both Paris and Brussels could suggest that a terrorist network in Europe has mastered the cooking and handling of TATP.

"There are actually very few bomb makers in the grand scheme of things," Castner said. "Once one finds a successful way to construct these things, they mass produce it."

While there are still few details about the devices used in the Belgium attacks, some reports indicate that the bombs at the airport were detonated within suitcases, while a suicide vest may have been used in the Metro bombing.

While a seemingly small distinction, the two delivery methods involve different constructions for the bomb maker. A TATP-loaded vest would be harder to build and maintain as the substance is so volatile. A suitcase loaded with TATP would be easier to transport and less likely to accidentally explode as the charges would more protected than if placed in a vest.

Reports on social media indicated that nails were used in the bombs. The type of fragmentation in explosives such as the ones used in Brussels often change between ball bearings, bolts, nails and anything else the bomb maker might decide to pack into the charges to increase the carnage.

Pictures posted online of three suspects pushing carts loaded with suitcases through the Zaventem airport show two of them wearing black gloves on their left hands. According to the Army technician, the gloves would be big enough to hold triggering devices for the bombs.

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