So far, no security system is in place at airports to detect these explosives, which explains why the global aviation industry is taking extraordinary measures to see that no 'liquid bomb' or the raw material for preparing one reaches the aircraft.

British authorities say the plot involved carrying separate components of liquid explosives in bottles and combining them into explosive cocktails aboard the aircraft. The detonation devices would be camouflaged as common electronic devices like mobile phones and I-pods. The terrorists may have invested in liquid peroxide-based explosives, which can be detonated with heat or an electric charge.

If successful, this plot could have caused far more damage than the attacks of September 11, 2001.

This is not the first time the terrorists had planned such an attack. A similar plot was hatched almost 12 years ago to simultaneously blow up a dozen airliners over the Pacific.

That idea was developed in Manila by Khalid Shaikh Mohammad, an understudy of Osama bin Laden, and Ramzi Yousef, who was also the mastermind of the 1993 bombing of the World Trade Center [Images].

The operation was code-named Bojinka. Similar to the recently foiled attempt, they were planning to put mixed chemicals into containers which would be smuggled aboard US bound flights from countries like South Korea and Hong Kong.

However, this was not supposed to be a suicide mission. The conspirators planned to place their devices onboard an aircraft and get off in transit before detonating them. The plot, however, was foiled in 1995 when a fire broke out in the apartment building where these people were working.

Owing to the massive crackdown post 9/11, terrorist organizations keep continuously changing their tactics, tools and targets for attack.

The London [Images] plot proves that the stringent security measures undertaken post 9/11 is no ground for complacency.

Over the years, terrorist organizations worldwide have used many different types of explosives for their attacks.

RDX: Forensic experts are still finding it difficult to identify the exact nature of explosive used during the recent Mumbai rail bombing. The latest indicator -- though not yet conclusive -- is that the terrorists used a mixture of RDX, ammonium nitrate and fuel oil, triggered by a mechanical timer with a Chinese-made battery.

Similar devices had been used in the past by jihadis belonging to the Harkat-ul-Jihad-al-Islami based in Bangladesh.

For many years RDX was the major explosive used in various terror attacks. There are many interpretations of its acronym including (but not limited to) Royal Demolition eXplosive, Research Department (composition) X, and Research Department eXplosive. The latter is most likely correct.

RDX in its pure synthesized state is a white, crystalline solid, which is usually mixed with other explosives. It has got a long history of usage, with both the Germans and the Allied Forces using it during World War II. Because of its military utility it is readily available and reasonably easy to procure. The techniques for using this explosive are well known and time-tested. This explosive was used by terrorist organizations with some success during the 1993 Mumbai blasts.

The IED: Another phrase frequently associated with terrorist attacks is the IED, or Improvised Explosive Device.

The IED is not a specific device, but a combination of various chemicals. They are normally pyrotechnic or incendiary chemicals. They are diverse in design and use mechanical or electrical type of initiation system. They range from crude designs which are mostly homemade, to highly sophisticated devices.

Organizations like the Al Qaeda [Images] and the Lashkar-e-Tayiba mostly use refined devices, proving their access to such technical expertise. Thirteen such devices were used in the 2004 Madrid (Spain) train bombings.

In years to come, there are significant chances that terrorist outfits may add chemical, biological or radiological material along with normal explosives to increase the lethality of the threat.

Dirty bombs: It is feared that they may even use a 'dirty bomb', because the radioactive material required for it can easily be procured from radiological laboratories attached to various hospitals and scientific establishments.

TATP: For the 7/7 London train blasts the terrorists had used acetone peroxide or TATP (TriAcetone TriPeroxide).

This explosive can be prepared with the help of commonly available acids such as sulphuric acid, acetone and hydrogen peroxide. Terror outfits like the Hamas also use TATP to carry out their suicide missions.

This is mainly 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 Briton Richard Reid had tried to detonate on a flight from Paris to Miami [Images] in December 2001.

Plastic explosive: Plastic explosive is another specialized form of explosive material which has been successfully used by some terrorist outfits. This is a soft and malleable substance which comes in various types. Till date terrorists have used plastic explosives like Semtex and C-4.

In October 2000, C-4 was used to launch an attack over the USS Cole, killing 17 sailors. In 1996, C-4 was used to blow up Khobar Towers, the US military housing complex in Saudi Arabia. C-4 has also been used in many of the Palestinian suicide bombings in Israel and the Israeli occupied territories. Semtex was probably the cause for the downing of PanAm flight 103 over Lockerbie. Semtex was used during the 1993 bombing of the US embassy in Nairobi.

Deadly phones: Recently, a unique way to use mobile phones as detonators was unearthed in the Kashmir valley. Till date, apart from grenade attacks, the valley has essentially been hit by conventional explosives, in the form of car or truck bombs.

The plot was exposed after it was noticed that militants were collecting mobile phone SIM cards. The plan: a kilogramme of high quality explosive, mostly RDX mixed with TNT, is linked to an activated mobile handset. The device can be set to go off when that number is called from anywhere in the world.

Post-2004, this technology is being effectively used by drug Mafia in the three southern provinces of Thailand which border Malaysia. Despite attempts by Thai authorities to register and track all mobile telephone use, bombs triggered anonymously by mobile phones continue to be used to detonate explosive devices. There are also reports that a digital wristwatch has been converted into a timer for a bomb.

Terrorist groups thus have an array of sophisticated explosives and detonators at their disposal, some of which can evade current detection systems.

The recent London crackdown has put the entire airline industry and the security apparatus into a tizzy, and it will take time for them develop countermeasures. But more importantly, the terrorist outfits have succeeded in creating panic, which is part of their agenda.

The need of the hour is to do a realistic assessment about the exact nature of explosive technologies the terrorists may have access to, and the actual repercussions of the use of these technologies.

The challenges of terrorism cannot be addressed by simply banning toothpaste and hair gel from cabin baggage.