The return to Bojinka principles is significant because it represents not only an IED attack against an aircraft but also a specific method of attack: a camouflaged, modular IED that the bomber smuggles onto an aircraft in pieces and then assembles once he or she is aboard and well past security. The original Bojinka plot used baby dolls to smuggle the main explosive charge of nitrocellulose aboard the aircraft. Once on the plane, the main charge was primed with an improvised detonator that was concealed inside a carry-on bag and then hooked into a power source and a timer (which was disguised as a wristwatch). The baby-doll device was successfully smuggled past security in a test run in December 1994 and was detonated aboard Philippine Air Flight 434. The main charge in the baby-doll devices, however, proved insufficient to bring down the aircraft, so the plan was amended to add a supplemental charge of liquid triacetone triperoxide (or TATP, aptly referred to as "Mother of Satan"), which was to be concealed in a bottle of contact lens solution. The plot unraveled when the bomb-maker, Abdel Basit (who is frequently referred to by one of his alias names, Ramzi Yousef) accidentally set his apartment on fire while brewing the TATP.

The Best Laid Plans

The 2006 liquid-bomb plot borrowed the elements of using liquid explosives and disguised individual components and attacking multiple aircraft at the same time from Bojinka. The 2006 plotters sought to smuggle their liquid explosives aboard using drink bottles, instead of contact lens solution containers, and planned to use different types of initiators. The biggest difference between Bojinka and more recent plots is that the Bojinka operatives were to smuggle the components aboard the aircraft, assemble the IEDs inside the lavatory and then leave the completed devices hidden aboard multi-leg flights while the operatives got off the aircraft at an intermediate stop. The more recent iterations of the jihadist airplane-attack concept, including Richard Reid's attempted shoe bombing and the 2006 liquid-bomb plot, planned to use suicide bombers to detonate the devices mid-flight.

The successful August 2004 twin aircraft bombings in Russia by Chechen militants also utilized suicide bombers. The shift to suicide operatives is not only a reaction to increased security but also the result of an evolution in ideology: Suicide bombings have become more widely embraced by jihadist militants than they were in the early 1990s. As a result, the jihadist use of suicide bombers has increased dramatically in recent years. The success and glorification of suicide operatives, such as the 9/11 attackers, has been an important factor in this ideological shift. One of the most recent suicide attacks was the Aug. 28 attempt by al Qaeda in the Arabian Peninsula (AQAP) to assassinate Saudi Prince Mohammed bin Nayef. In that attack, a suicide operative smuggled an assembled IED containing approximately one pound of high explosives from Yemen to Saudi Arabia concealed in his rectum. While in a meeting with Mohammed, the bomber placed a telephone call and the device hidden inside him detonated.

In an environment where militant operational planning has shifted toward concealed IED components, this concept of smuggling components such as explosive mixtures inside of an operative poses a daunting challenge to security personnel — especially if the components are non-metallic. It is one thing to find a quantity of C-4 explosives hidden inside a laptop that is sent through an X-ray machine; it is quite another to find that same piece of C-4 hidden inside someone's body. Even advanced body-imaging systems like the newer backscatter and millimeter wave systems being used to screen travelers for weapons are not capable of picking up explosives hidden inside a person's body. Depending on the explosive compounds used and the care taken in handling them, this method of concealment can also present serious challenges to explosive residue detectors and canine explosive detection teams. Of course, this vulnerability has always existed, but it is now highlighted by the new tactical reality. Agencies charged with airline security are going to be forced to address it just as they were previously forced to address shoe bombs and liquid explosives.

Who's Involved

Currently, there are three different actors in the jihadist realm. The first is the core al Qaeda group headed by bin Laden and Ayman al-Zawahiri. The core al Qaeda organization has been hit hard over the past several years, and its operational ability has been greatly diminished. It has been several years since the core group has conducted a spectacular terror attack, and it has focused much of its effort on waging the ideological battle as opposed to the physical battle. The second group of actors in the jihadist realm involves the regional al Qaeda franchise groups or allies, such as al Qaeda in the Arabian Peninsula, Jemaah Islamiyah and Lashkar-e-Taiba. These regional jihadist groups have conducted many of the most spectacular terrorist attacks in recent years, such as the November 2008 Mumbai attacks and the July 2009 Jakarta bombings. The third group of actors is the grassroots jihadist militants, who are essentially do-it-yourself terrorist operatives. Grassroots jihadists have been involved in several plots in recent years, including suicide bomb plots in the United States and Europe. In terms of terrorist tradecraft such as operational planning and bomb-making, the core al Qaeda operatives are the most advanced, followed by the operatives of the franchise groups.

The grassroots operatives are generally far less advanced in terms of their tradecraft. However, any of these three actors are capable of constructing a device to conduct an attack against an airliner. The components required for such a device are incredibly simple — especially so in a suicide attack where no timer or remote detonator is required. The only components required for such a simple device are a main explosive charge, a detonator (improvised or otherwise) and a simple initiator such as a battery in the case of an electric detonator or a match or lighter in the case of a non-electric detonator. The October 2005 incident in which a University of Oklahoma student was killed by a suicide device he was carrying demonstrates how it is possible for an untrained person to construct a functional IED. However, as we have seen in cases like the July 2005 attempted attacks against the London Underground and the attempted strikes in July 2007 against nightclubs in London and the airport in Glasgow, grassroots operatives also can botch things, due to a lack of technical bomb-making ability.