Terrorist organizations are fast becoming innovative and technology savvy. The recent plan foiled by British agencies was to blow up ten commercial airliners flying from Britain to the United States by using liquid explosives. Interestingly, it has been reported that the aviation industry knew of the possibility for many years that such tactics could be used by terrorist organizations but did little to devise effective countermeasures. This plot revealed by the British authorities involved using the chemical properties of liquids and gels to convert them into explosives. The plan involved carrying different fluids in soft drink bottles and mixing them together on the aircraft to produce an explosive. This would then be detonated with electronic devices like mobile phones, Ipods etc. The terrorists may have invested in liquid-peroxide-based explosives which are sensitive to heat, shock and friction. They are capable of detonation by heat or an electric charge.

There are different opinions regarding the exact methodologies available for isolating liquid explosives during routine security checks at airports. Some Israeli analysts claim that such techniques are available but are time-consuming. Others believe that the aviation security system is defenseless against such attacks and the present X-ray machines and metal detectors in airports cannot identify liquid explosives. Essentially, most of the tools designed for identification of liquid explosives are expected to be software based tools. Image analysis software can be attached to existing X-ray scanners and this would help match the density of known explosives. The problem with explosives identification is that they look like organic matter and can be molded into any shape, making shape recognition almost impossible. The software basically bombards the image with algorithms that identify unique areas of interest. Within a few seconds the software establishes unique signatures of the volatile nature of the liquid.

Many analysts believe that the aim of terrorist organizations may have been to carry a substance into the aircraft that may have been a liquid form of TATP (triacetone triperoxide). This explosive can be manufactured in both liquid and powder form, and can be manufactured with commonly available acids like sulfuric acid, acetone and hydrogen peroxide. TATP can be detonated with or without a classic detonator. Its ingredients (various chemicals) are so volatile that an explosion can be created by dropping a container with such materials to the floor.

During the 7/7 London train blasts the terrorists had used Aectone peroxide or TATP. Terror outfits like Hamas also use TATP to carryout their suicide missions because TATP is almost undetectable by sniffer dogs or conventional bomb detection systems. The same substance was integrated as the trigger in the shoe bomb that British national Richard Reid had tried to detonate on a flight from Paris to Miami in December 2001.

Many feel that the West is overreacting to this threat and are unnecessarily harassing air travelers. However, banning a variety of liquids, aerosols and gels from airplanes is essential to eliminate several liquid or liquid-like explosives being carried inside the aircraft. Moreover, liquid explosives like nitro methane can be converted into a gel from a liquid state and can be carried inside a toothpaste tube. Explosives like TATP are capable of making a hole in the hull of a heavy ship, let alone the metal body of an aircraft.

At the same time, few scientists believe that this is not as simple a task as is made out to be where by just mixing two liquids one can create a liquid explosive. This is because preparing liquid explosives is an extremely delicate process, particularly carried out at low temperatures. It is not possible to carryout the process in an aircraft restroom.

Presently, it appears that less amount of technical knowledge and equipment is available to effectively handle the liquid explosive threat. Under these circumstances it is better to resort to restrictions on what to carry and what not to carry by the aircraft passengers. However, this should not become a solution of choice because the process of checking is time consuming, and will hamper the commercial interests of the industry in the long run. The present ingenuity and technology friendliness shown by the terrorists clearly indicates that terrorists could always find different ways to harass a state. Technical countermeasures to address such threats could be a short-term solution, but what is required most is to invest in good intelligence to deal with the real causes of terrorism.

Views expressed here are the author's own.