A recent bomb plot linked to Al Qaeda has exposed a critical vulnerability in aviation security.
The bombs - concealed in toner cartridges shipped from Yemen - were loaded with lethal amounts of Pentaerythritol tetranitrate, or PETN.
Fortunately, at least one of the devices, located in a package addressed to a Chicago-area synagogue, was intercepted in Britain before being shipped to the US on a commercial cargo plane.
A second PETN bomb addressed to another Chicago synagogue was later identified and disarmed in Dubai.
"[The bomb] was one of the most sophisticated we've seen. [This is because] the naked eye won't pick it up, experienced bomb officers did not see it [and] x-ray screening is highly unlikely to catch it," a British counter-terrorist expert told the Guardian.
"[Unfortunately], there is [still] no way of [positively] picking out PETN. It is a continued vulnerability [and these bombs] were [certainly] sophisticated, [lethal] and very well-disguised."
Meanwhile, UK explosives expert Sidney Alford told CNN that the PETN-laden bombs likely contained between two-and-a-half and three-and-a-half kilos of the dangerous substance.
"That would be a murderous amount in an airplane. They are [obviously] getting technically better," said Alford.
"And the means of initiation appears to have been mobile telephones [using electric circuits connected to cell phone chips], meaning they will go off wherever they happen to be when you dial the number. [Still], the the circuitry was messy. They are [somewhat] behind the times with explosives."
Nevertheless, the Israeli-based DEBKAfile assesses that Al Qaeda managed to "chalk up a [major] coup" by successfully penetrating and paralyzing global intercontinental air mail systems.
"While only two packages have been identified as dangerous, there may be more still be found in meticulous sweeps of many tons of freight - or even delivered.
"[Clearly], the imposition of heightened security for air cargo comparable to that applied to passenger traffic would throw the mail industry into chaos, causing extreme financial losses and disrupting an important branch of the Western economy.
"And that too would be accounted by al Qaeda a major success - at very little cost to itself."