The Terrorists' Secret Weapon

Intelligence experts have heard chatter for months about the explosive allegedly used by the underwear bomber. So why has the U.S. cut back on machines that detect it?

Editor's Note: In an earlier version of this article, a paragraph was paraphrased from a New York Times report and a phrase was copied from a Reuters report, both without attribution. The Daily Beast has removed the paragraph and attributed the phrase, and regrets the error.

U.S. security officials had become increasingly worried in the months leading up to the attempted airplane bombing on Christmas Day about terrorists using the explosive agent concealed by Umar Farouk Abdulmutallab, several counterterrorism experts tell The Daily Beast. Internet chatter about PETN spiked over the summer, as monitored by U.S. intelligence services, the sources add.

Yet over the past 18 months, a Transportation Security Administration employee tells me, the U.S. has stopped using more than half of the Explosive Trace Portals that have capability of detecting PETN. These are dubbed “puffer” machines because they release several puffs of air to shake loose trace explosive particles as passengers walk through. The TSA employee, who spoke to The Daily Beast on the condition of anonymity and does not agree with the reduced use of puffers, says that there are fewer than 40 machines deployed today, down from 94 in service (and more than 200 purchased).

Since the 9/11 attacks, the government has spent more than $40 billion in security enhancements at American airports, and yet, ironically, maintenance costs are privately blamed for the cutback in the use of PETN-detecting puffer machines.

Deployment of even more effective, and far more expensive, screening devices—full-body scanners—has been slowed by political wrangling, primarily over privacy concerns because the scans reveal "passengers 'naked' to the operators and anyone else passing by the machine's screen," according to Reuters. One frustrating note: The U.S. had purchased and installed in 2008 full-body scanners for the Lagos airport, where Abdulmutallab began his journey. Rep. Peter King (R-NY) has told reporters that Abdulmattallab was not subjected to a full-body scan either at Lagos or subsequently at Amsterdam’s Schiphol Airport, where Dutch have made the scanner’s use “voluntary.”

Michael Chertoff: Letting Down Out GuardConor Friedersdorf: Passengers Fight BackReihan Salam: Heckuvajob, NapolitanoThis cutback in puffers and delay in deploying scanners occurs as officials are increasingly worried about a successful PETN terrorist attack on a future flight. “PETN is one of the ideal terror weapons because the technology to detect it is not widely available,” says an senior U.S. intelligence analyst, who also spoke on the condition of anonymity.

PETN, or pentaerythritol tetranitrate, has been a been a major security concern ever since Richard Reid, the so-called shoe bomber, tried blowing up a trans-Atlantic flight with it in 2001, according to these sources. It’s an innocuous looking white powder that at first glance could pass as sugar or salt. With food coloring, it can be disguised as ground coffee. It’s a major ingredient in Semtex plastic explosives and also, like its chemical cousin, nitroglycerin, PETN is used medically as a vasodilator (expanding the blood vessels) in treating heart conditions. It’s not very volatile, which means it’s good for a terrorist who doesn’t have to worry about early detonation. The attempted Christmas bomber, Abdulmutallab, had a six-inch long packet of PETN sewn into his underpants. That packet weighed 80 grams (2.8 ounces). As little as six grams could blow a hole in the metal hull of a commercial plane.

An FBI counterterrorism official told The Daily Beast that the reason the PETN did not explode is that the glycol-based liquid meant to detonate it instead melted the plastic hypodermic syringe Abdulmutallab was carrying. Fortunately for the crew and passengers, the liquid didn't make enough contact with PETN to create an explosion. (The failure to detonate the bomb is evidence to counterterrorism officials that Abdulmutallab most likely was not the bomb maker, not intimately familiar with it, and was only instructed on how to set it off.)

Since the shoe bomber had converted his sneakers into PETN bombs, international airport security has required passengers remove their shoes and pass them separately through X-ray machines. But that’s just to spot whether there is anything unusual in the shoe, like wiring or a makeshift detonator fuse. Those X-ray units cannot detect PETN.

Hence, the worries about precisely what happened on Christmas Day. “PETN can easily be stitched into clothing and hidden around the body,” an FBI agent familiar with the explosive tells me. “And what if it’s hidden in a body cavity? No one is going to find it then.” Drug mules typically carry heroin on international flights, hidden in sealed condoms they’ve swallowed. In the case of an explosive like PETN, security experts are worried about the terrorist who might hide the small amount of powder in a condom inserted in his anus. “Without a strip search, you are never going to find it,” says the FBI agent. He then went on to give very scary details about how this powder could be deployed for maximum damage.

Since the 9/11 attacks, the government has spent more than $40 billion in security enhancements at American airports, and yet, ironically, maintenance costs are privately blamed for the cutback in the use of puffer machines. At their peak, the TSA had bought 207 at a cost of $30 million and had deployed 94 at 37 airports. But the units required about $15,000 on average annually in maintenance, and operators had to be finely trained to operate them correctly. TSA officials refused to confirm or deny their employee’s estimate that fewer than 40 are deployed today.

Bomb-sniffing dogs can also detect PETN. Well-trained dogs can also sniff out particles left on a bomber’s clothing or body from having handled the powder. But Abdulmutallab did not evidently encounter dogs when he traveled from Nigeria to Amsterdam and then to Detroit. He did pass through at least one, and probably two magnetometers, the conventional metal detectors used at most airports. While they are good at finding firearms, box cutters, and nail clippers, they are useless in detecting explosives.

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As for the full-body scans, they are in use at only six airports nationwide. Despite the failed Christmas Day bombing, Rep. Jason Chaffetz (R-UT) is still trying to ban the machines as a primary screening tool. His legislation, which would allow the TSA to use them only as a secondary tool after someone has raised suspicion, passed the House this year, but is stalled in the Senate.

Chaffetz’s office did not respond to request for comment. But the congressman told The Salt Lake City Tribune, "It's a difficult balance between protecting our civil liberties and protecting the safety of people on airplanes. I believe there's technology out there that can identify bomb-type materials without necessarily overly invading our privacy."

Chaffetz and his supporters cite heat sensors as an alternative to the full-body scanners. But that technology is not perfected, and has not been deployed at any airports.

As technology changes, so do the threats facing counterterrorism experts and airport security teams. What happens now when a passenger with a heart condition shows up with a prescription for Lentonitrat, which is nearly pure PETN? And what if they are also a diabetic and are traveling with a syringe of what they say is insulin. “Even with the all the bells and whistles,” an FBI counterterrorism official tells The Daily Beast, “it is still very difficult. We have to be right 100 percent of the time. They only have to get lucky once.”

Gerald Posner is former chief investigative reporter for The Daily Beast. He's the award-winning author of 10 investigative nonfiction bestsellers, on topics ranging from political assassinations, to Nazi war criminals, to 9/11, to terrorism. His latest book, Miami Babylon: Crime, Wealth and Power—A Dispatch from the Beach, was published in October. He lives in Miami Beach with his wife, the author Trisha Posner.