24-03-2016, 02:29 PM
http://www.nytimes.com/2016/03/24/world/....html?_r=0
The announcement by the Belgian authorities that they had confiscated more than 30 pounds of the explosive TATP from a dwelling used by the attackers in Brussels was, in some ways, an expected development. But it contained one detail that bomb-disposal technicians and security officials regarded with surprise: the quantity of the particular explosive involved.
TATP, also known as triacetone triperoxide, is a white, crystalline explosive also used in the attacks in Paris in November, though it caused few casualties compared with the terrorists' assault rifles. Highly unstable and sensitive to shock, friction and heat, it breaks down quickly in air. And while it can be made with basic chemistry skills and relatively simple equipment, it is more dangerous and tedious to manufacture than a commonly used fertilizer-based explosive, ammonium nitrate, which an American official, citing intelligence shared by Belgium, said the attackers had also used.
Unlike ammonium nitrate, TATP is typically seen in small quantities, not in the tens of pounds. One American official who had reviewed the intelligence related to the bombs in France and the newer intelligence from Belgium said the recovery of more than 30 pounds indicated an increased capacity since the Paris attacks. And that figure did not include any explosive actually used in the bombs that killed 31 people on Tuesday.
The Belgian authorities also said they had recovered nearly 40 gallons of acetone and eight gallons of hydrogen peroxide, materials used in producing TATP. They made no mention of the acids needed as catalysts or chemicals often used to rinse TATP crystals and remove impurities.
The quantities of explosives and precursors, the American official said, raised questions about how the terrorists were able to elude detection, especially during a manhunt for Salah Abdeslam, the suspect in the Paris attacks who was arrested last week.
Making TATP typically requires meticulous, time-consuming work, adding the catalyst, drop by drop, to a mixture that must be stirred and kept cool, often with a large quantity of ice.
Without specialized equipment, little can be rushed. Adding the catalyst too quickly can lead to aggressive bubbling and rising temperatures. If the reaction gets too hot, it can cause inadvertent explosions.
Even after TATP precursors are acquired, its manufacture can attract attention, because some of the chemicals often involved can generate strong odors.
Drying TATP at room temperature, a last step after rinsing and filtering, also requires a fairly large area, another American official said, unless a vacuum drying chamber is involved. At that point, the TATP would be stored in a relatively airtight container, but if pure, it could not be stored long. After a few weeks, it would be much less powerful.
The intelligence on the explosives suggested that the attack could have been more lethal, the first official said, because two improvised explosive devices constructed with TATP, ammonium nitrate, and a mix of metal bolts and nails were found in suitcases, undetonated, at the airport. A suicide belt was also recovered at the airport, and two more suitcases with bombs were later confiscated during a sweep of a residence used by the suspects.
The technicians noted that TATP would be a logical third choice for terrorists who could not obtain conventional explosives or precursors for the safer-to-handle and easier-to-make fertilizer-based explosives, which are a staple of terrorist and insurgent bombing campaigns in Afghanistan and the Middle East.The damage at the airport suggested a blast wave associated with a relatively large amount of an explosive, three American bomb-disposal technicians said. The terrorists' reliance, at least in part, on TATP was a predictable adaptation to the security climate in Europe, where urban residents buying fertilizer in large quantities might attract attention that purchases of TATP precursors would not.
The officials and bomb-disposal technicians requested anonymity because they were not authorized to speak to reporters.
The Belgian authorities did not immediately release further details of the bombs used in Brussels, including the means by which they were detonated. But like ammonium nitrate, TATP has a substantial history in terror attacks, although it is more commonly seen as a detonator or the explosive in a makeshift blasting cap, as opposed to a main charge.
The officials noted that in the Paris attacks, TATP had been used as a main charge packed into smaller, plate-like bundles that were sealed with tape and inserted in suicide vests. The tape was apparently intended to limit the explosive's exposure to oxygen and slow its decay.
The bundles in Paris had also, in at least one instance, been spiked with what an official called "enhancements" bits of metal designed to be propelled by the blasts, making the bombs more deadly. This has long been a feature of makeshift bombs, including the unexploded devices recovered in Belgium this week.
The announcement by the Belgian authorities that they had confiscated more than 30 pounds of the explosive TATP from a dwelling used by the attackers in Brussels was, in some ways, an expected development. But it contained one detail that bomb-disposal technicians and security officials regarded with surprise: the quantity of the particular explosive involved.
TATP, also known as triacetone triperoxide, is a white, crystalline explosive also used in the attacks in Paris in November, though it caused few casualties compared with the terrorists' assault rifles. Highly unstable and sensitive to shock, friction and heat, it breaks down quickly in air. And while it can be made with basic chemistry skills and relatively simple equipment, it is more dangerous and tedious to manufacture than a commonly used fertilizer-based explosive, ammonium nitrate, which an American official, citing intelligence shared by Belgium, said the attackers had also used.
Unlike ammonium nitrate, TATP is typically seen in small quantities, not in the tens of pounds. One American official who had reviewed the intelligence related to the bombs in France and the newer intelligence from Belgium said the recovery of more than 30 pounds indicated an increased capacity since the Paris attacks. And that figure did not include any explosive actually used in the bombs that killed 31 people on Tuesday.
The Belgian authorities also said they had recovered nearly 40 gallons of acetone and eight gallons of hydrogen peroxide, materials used in producing TATP. They made no mention of the acids needed as catalysts or chemicals often used to rinse TATP crystals and remove impurities.
The quantities of explosives and precursors, the American official said, raised questions about how the terrorists were able to elude detection, especially during a manhunt for Salah Abdeslam, the suspect in the Paris attacks who was arrested last week.
Making TATP typically requires meticulous, time-consuming work, adding the catalyst, drop by drop, to a mixture that must be stirred and kept cool, often with a large quantity of ice.
Without specialized equipment, little can be rushed. Adding the catalyst too quickly can lead to aggressive bubbling and rising temperatures. If the reaction gets too hot, it can cause inadvertent explosions.
Even after TATP precursors are acquired, its manufacture can attract attention, because some of the chemicals often involved can generate strong odors.
Drying TATP at room temperature, a last step after rinsing and filtering, also requires a fairly large area, another American official said, unless a vacuum drying chamber is involved. At that point, the TATP would be stored in a relatively airtight container, but if pure, it could not be stored long. After a few weeks, it would be much less powerful.
The intelligence on the explosives suggested that the attack could have been more lethal, the first official said, because two improvised explosive devices constructed with TATP, ammonium nitrate, and a mix of metal bolts and nails were found in suitcases, undetonated, at the airport. A suicide belt was also recovered at the airport, and two more suitcases with bombs were later confiscated during a sweep of a residence used by the suspects.
The technicians noted that TATP would be a logical third choice for terrorists who could not obtain conventional explosives or precursors for the safer-to-handle and easier-to-make fertilizer-based explosives, which are a staple of terrorist and insurgent bombing campaigns in Afghanistan and the Middle East.The damage at the airport suggested a blast wave associated with a relatively large amount of an explosive, three American bomb-disposal technicians said. The terrorists' reliance, at least in part, on TATP was a predictable adaptation to the security climate in Europe, where urban residents buying fertilizer in large quantities might attract attention that purchases of TATP precursors would not.
The officials and bomb-disposal technicians requested anonymity because they were not authorized to speak to reporters.
The Belgian authorities did not immediately release further details of the bombs used in Brussels, including the means by which they were detonated. But like ammonium nitrate, TATP has a substantial history in terror attacks, although it is more commonly seen as a detonator or the explosive in a makeshift blasting cap, as opposed to a main charge.
The officials noted that in the Paris attacks, TATP had been used as a main charge packed into smaller, plate-like bundles that were sealed with tape and inserted in suicide vests. The tape was apparently intended to limit the explosive's exposure to oxygen and slow its decay.
The bundles in Paris had also, in at least one instance, been spiked with what an official called "enhancements" bits of metal designed to be propelled by the blasts, making the bombs more deadly. This has long been a feature of makeshift bombs, including the unexploded devices recovered in Belgium this week.