08/09/2013 -Recent media reports regarding impending al-Qaeda sponsored terror attacks across the Middle East and Africa also reported that the attacks were to involve a different kind of explosives using a new "ingenious" type of liquid explosive.

U.S. intelligence sources say the "ingenious" process involves dousing ordinary clothes in an unknown liquid explosive. Once dry, the liquid becomes virtually undetectable by current security measures. Visually, the process can described as a typical t-shirt which, upon being ignited by a flammable substance or detonated using unknown sophisticated methods, could be blown up causing mass damage around its perimeter.

Furthermore, sources point out that the liquid explosive, thought to be a new and improved version of the underwear bomb, has been devised by Yemen-based al-Qaeda affiliate and mastermind bomb expert Ibrahim al-Asiri of "al-Qaeda in the Arabian Peninsula," or AQAP.

Assuming the information regarding this "new" type of explosive to being partially accurate, we must consider the implications for homeland security and, more specifically, for those responsible for aviation security.

Firstly, it should be said that clothes saturated with explosives is far from a new phenomenon. We can trace the roots of cloth-saturated explosives back to roughly 1846. In this instance, Mr. Christian Friedrich Schönbein, a German-Swiss chemist, was working in the kitchen of his home in Basel when he spilled a bottle of concentrated nitric acid on the kitchen table. He reached for the nearest cloth, a cotton apron, and wiped it up after which he hung the apron on the stove door to dry. As soon as the apron was dry, there was a flash as it exploded. His preparation method was the first to be widely imitated, thus inventing the "gun cotton" explosive a former widely used military standard explosive.

Terrorists have been using cotton saturated with explosives as a concealment method for a number of attacks. The most prominent case is the infamous "Bojinka Plot." In this case, a jihadist terrorist cell headed by Ramzi Yousef and Khalid Sheikh Mohammed were in the advanced stages of planning to blow up 11 U.S. airliners departing from airports in South East Asia for the United States. Fortunately, the plot was disrupted in 1995. However, the terrorist had intended to use IEDs that were concealed inside dolls saturated with liquid explosives as the main charge.

In August 1971 two young French sisters were arrested on arrival to Ben Gurion airport following intelligence information regarding an impending terrorist attack. A search of the two sisters’ suitcases did not at first reveal anything suspiciou--only clothes and shoes. A more thorough search found that the clothes weighed double the expected weight and were found to be impregnated with explosives. We can also note again in Israel, in 2004 and 2005, there were several cases in which suicide bombers were caught at different border crossings wearing explosive pants that they intended to detonate in public areas. The IEDs they were wearing were saturated with EGDN explosives. Both IEDs were fully functional and detonated by the Israeli bomb squad.

We believe that what we are hearing in the report, again if partially correct, is certainly not a new terrorist modus operandi or a new type of explosive. What we may be observing is the return of an old and known modus operandi. However, policy makers must ensure that current security procedures are capable of meeting all relevant threats, including those from the past.

It is important to remember that in the summer of 2006 when details of the thwarted "Transatlantic Liquids Plot" became known, many security policy makers at the time spoke of the need for new security measures to deal with the "new threat" of liquids explosives. It seemed to have been forgotten that in November 1987 Air Korea flight 858 was blown up in midair by an explosive device with the main charge being 1 liter of PLX, a liquid explosive. Clearly, the foiled Bojinka Plot in 1995, discussed above, must also be included in the list of case studies.

While this tactic may not be new, terrorists will continue to develop new means of attack and creative modus operandi aimed at defeating and circumventing security measures in place. It continues to be our view that it is not feasible to screen every passenger to the level required that will enable the detection of all threats. In order to detect the sophisticated threats that the terrorists are capable of initiating, including old tactics that become new again, a risk-based screening system is essential. Fortunately, most aviation security regulators recognize this and are moving in the right direction with behavioral detection programs and differential screening levels.

David Harel is a member of ASIS International and the managing director at ASERO in Tel Aviv, Israel. He is an expert in terrorism.