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Foiling the plot

Time Magazine has an overview of how the airline terror plot was foiled. According to Time

Britain's MI-5 intelligence service and Scotland Yard had been tracking the plot for several months, but only in the past two weeks had the plotters' planning begun to crystallize, senior U.S. officials tell TIME. In the two or three days before the arrests, the cell was going operational, and authorities were pressed into action. MI5 and Scotland Yard agents tracked the plotters from the ground, while a knowledgeable American official says U.S. intelligence provided London authorities with intercepts of the group's communications.

According to CNN a British agent infiltrated the cell.

Does that mean that the agent only infiltrated the group in the past two weeks? And if there was an agent undercover among the plotters, why was there a need for American intercepts?

(2 things. 1) This reporting is still preliminary maybe some details are not 100% correct. 2) You might want as much intelligence on an operation like this however it is obtained.)

According to CNN

Among those arrested were a Muslim charity worker and a Heathrow Airport employee with an all-area access pass, according to Britain's Channel 4.

There are often complaints that it's unfair to shut down Muslim charities. This suggests (but doesn't prove) that at least some of them have secondary functions too.

The plotters were planning to use liquid based explosives. (Time again)

The FBI-DHS report next warns law enforcement agencies about the two peroxide-based liquid explosive that could be used in a future attack against the U.S.--triacetone triperoxide (TATP) or hexamethylene triperoxide diamine (HMTD). The report describes how a terrorist would assemble bombs with these chemicals. Peroxide-based liquid explosives "are sensitive to heat, shock, and friction, can be initiated simply with fire or electrical charge, and can also be used to produce improvised detonators," the report states. "For example, TATP or HMTD may be placed in a tube or syringe body in contact with a bare bulb filament, such as that obtained from inside a Christmas tree light bulb, to produce an explosion." The report doesn't mention anything about a terrorist assembling such a bomb on a plane, but it does warn that manufacturing such a device can be dangerous for the bombmaker. "Because of the instability of these substances," the report notes, "spontaneous detonation can occur during the production process."

So this is a risky way to go about planning a terror attack. The planners were probably susceptible to "work accidents."

Time also has a feature Why Liquid Explosives May Be Terror's Secret Weapon that tells us

Liquid explosives also attack airline security's weakest point — the Transportation Security Administration screeners. They are the burger-flippers of the entire security system, and the chances of even the best of them visually identifying a liquid explosive in an innocuous bottle are slim — that's why Israel's Ben Gurion airport has a laboratory in the basement to conduct instant tests of liquids found on suspect passengers. If the U.S. system lacks sufficient technology to detect liquid explosives, and if it relies on the TSA screeners to ID possible terrorists, it is, at best, a wire mesh fence.

So using liquid explosives is a sign that the screening and security procedures put into place post 9/11 possibly have been successful in preventing other plots.

Israel's Technion has developed a device for detecting TATP. The article promoting the device also explains (technically) how TATP works

"Most explosives are energetic materials," explains Keinan. "They have a lot of energy chemically stored in them. In an explosion, that energy is released suddenly, generating a huge amount of heat. The heat in turn creates the explosive expansion." To get the energy into the explosive in the first place, it has to be supplied from something, generally in the form of heat. TNT, for example, has to cooked at high temperature for its high-energy chemical bonds to form. Since nitrogen compounds are good at storing energy, most conventional explosives contain nitrogen, a property that makes them relatively easy to detect.

But TATP is different. It is formed at room temperature and does not require any input of heat. Nor does it contain nitrogen compounds. It is in fact a carbohydrate-type compound somewhat related to sugar. So the question is--how can it explode if the energy is not pumped into it in the first place?

The research team demonstrated that TATP exploded not by releasing thermal energy, but by suddenly breaking each molecule of TATP in the solid state into four molecules of gas. Although the gas is at room temperature, it has the same density as the solid, and four times as many molecules, so it has 200 times the pressure of the surrounding air. This enormous pressure – one-a-half tons per square inch – then pushes outward, creating an explosive force 80% greater than that of TNT.

"There is no increase in energy when the molecules break apart," says Keinan, "but there is a sudden increase in entropy." Entropy is a measure of the degree of disorder in a system, and the randomly moving gas molecules have far more entropy than the orderly TATP crystal from which they are produced. When entropy increases in a system, energy can be derived from it, such as the kinetic energy of an explosion. In a TATP explosion, the gas molecules give up their energy of motion to the surroundings, in the process creating the shock wave that does the damage.

In terms of airline security, the problem with the device developed by the Technion is that it requires a sample of the material for testing. So the suspected material still needs to be identified. It is not a passive detector, like a metal detector. This would mean that an effective procedure for detecting such materials would increase the wait at airports significantly.

Technorati tags: War on Terror, TATP.