U.S. intelligence sources say security teams surrounding the upcoming inauguration of U.S. President George W. Bush will pay special attention to limousines. The increased concern results from a report seized in 2004 from al Qaeda that examines the possibility of using limousines rigged with cylinders of flammable gas as mobile suicide bombs.
STRATFOR has discussed the possibility that terrorists could use limousines to stage bombings or to conduct covert surveillance of targets. Limousines often are able to gain access to places that normal vehicles cannot — as it generally is assumed that they are transporting legitimate VIPs — while their darkly tinted windows conceal both the occupants and their cargo. Because of the assumption about their passengers and their ubiquity at high-profile functions, limousines often are overlooked — although STRATFOR suspects that an attack during the Bush inauguration is highly unlikely, precisely because of the tight security surrounding the event, which includes the installation of barriers aimed at preventing vehicle-borne suicide attacks.
According to U.S. intelligence sources, the seized al Qaeda document outlines a scenario in which three limousines would be deployed, each carrying at least a dozen compressed-gas cylinders that would be used to create a fuel-air bomb. The document, however, does not outline a specific attack plan and does not mention the United States in general or the inauguration specifically. The government response to this as regards the inauguration, therefore, is another precautionary measure.
Militant fascination with flammable gas is not new. Al Qaeda and other groups have long sought to augment the destructive power of traditional explosives by using gases to create fuel-air explosives. The U.S. and Russian militaries both use fuel-air bombs with devastating success — perhaps one reason for the militant interest. Creating such a bomb, however, is far easier said than done. A fuel-air explosion requires a precise mixture of explosive vapor to the surrounding air, and the ratio varies depending on the fuel. Methane and propane, for example, require different mixtures in order to ignite with any efficacy. Even a well-trained militant would have a difficult time producing such an explosion — though that has not prevented attempts. In 1983, when pro-Iranian militants targeted the U.S. Embassy in Kuwait City in a series of vehicle bombings that killed five people and wounded 83 others, the vehicles were rigged with cylinders of flammable gas in addition to conventional explosives. The FBI also found evidence that propane was used in the 1983 bombing of the U.S. Marine barracks in Beirut, Lebanon, which killed 241 people. In 1993, World Trade Center bomber Ramzi Yousef put three cylinders of hydrogen in a truck containing his bomb in an attempt to multiply its destructive power. In this case, the concept of using gas cylinders to enhance the effect of an improvised explosive device was taken out of a manual found in the possession of Yousef's coconspirator Ahmed Ajaj, who obtained the manual while attending a training course at Osama bin Laden's Khaldan training camp in Afghanistan in 1992. The 2002 Bali, Indonesia, car bombing outside of a nightclub, which killed 202 people, also involved flammable gas cylinders. In Tunisia that same year, a propane tanker was used in a truck bombing at a synagogue that killed 18 people. Former al Qaeda operative Jose Padilla also explored the possibility of using natural gas to destroy high-rise apartment buildings. In all of these cases, the destruction would have been a great deal worse had the devices actually caused the fuel-air explosion their builders hoped to create. In fact, it could be argued that accidental fuel-air explosions are more likely to occur than intentional ones, though the accidental nature of the explosion does not mitigate its disastrous effects — as evidenced by explosions in coalmines, at natural gas pipelines or plants, and even at grain silos. In March 2004, for example, 43 people were killed in an accidental natural gas explosion in an apartment block in Russia's White Sea port of Arkhangelsk. Despite the technical difficulties associated with creating fuel-air bombs, the potential destructive power of these bombs — and the ease of obtaining the necessary supplies — is more than enough motivation for militants to continue testing them. Odds are, they eventually will get it right.