Two points are important to bear in mind in weighing this intelligence: First, the information is dated — perhaps as much as four years old — and might not be indicative of current al Qaeda plans. However, the group’s methodological planning and target selection indicates that it probably works from a long list of tactical scenarios, from which the best option for a specific operation can be chosen. That said, the use of helicopters and limousines offers up some intriguing possibilities for anyone planning a strike in New York.
In the case of limousines, the tactics would be very similar to those commonly used in deploying a standard vehicular bomb — but with the added benefit of better physical access to VIPs and targeted buildings.
Past al Qaeda plots have centered on the use of delivery trucks or vans, into which large cargos of explosives can be packed in order to create a catastrophic explosion. However, access for delivery vehicles is restricted in many commercial areas to back entrances and the like — which then affects the nature of casualty counts. From a militant’s perspective, car bombs might have better access to a target facility, such as a hotel, but by dint of their size cannot carry as much explosive material. Limousines, however, are an ideal compromise: They combine both sizeable cargo capacity and — especially in places like New York City — optimum access to important buildings, where limo occupants would enjoy door-to-door service.
Moreover, limousines in New York — especially those with VIP placards issued by the New York Police Department — have virtual carte blanche in terms of where they are parked and how they are allowed to approach buildings. These regulations have not changed much since the Sept. 11 attacks.
As a result, it is entirely possible to imagine a limousine tagged with stolen or counterfeit placards pulling up to the entrance of a four-star hotel or targeted office building, such as the Citigroup Center, and explosives being detonated before any alarms could be triggered. Such an attack would cause severe damage to the front of the building and numerous casualties within the lobby and entrance areas. From a protective security perspective, this would be a highly difficult threat to guard against: If a hostile limousine driver were able to approach the building’s entrance, it would be too late to counteract the attack. Street closures and standoff distance are options, as are chokepoints at which authorities could search vehicles for explosives — but the downside to any of these measures would be gridlock in the city.
The recent intelligence also pointed to the possibility that militants might use helicopters to attack New York City. We believe this to be a less likely scenario than the risk of a truck or limousine bombing — partly because helicopters are less widely available, and training is needed in order to pilot one. However, helicopters are more maneuverable than fixed-wing aircraft and thus provide a number of attack options. Moreover, al Qaeda conducted surveillance on heliports in midtown Manhattan in 1992, in connection with a plot against then-President Bill Clinton — something that lends credence to the intelligence gathered.
Although their size and the lower speed at which they travel, in relation to airplanes, would make helicopters less effective if used as missiles, their maneuverability would make them ideal for carrying out targeted strikes — for instance, perhaps zeroing in on certain floors of a building. Additionally, helicopters are used as commuter transport by many executives and have other civilian uses — such as for medical emergencies and traffic monitoring — and thus arouse little notice. In New York City, regulations for aircraft flying below 2,000 feet (encompassing both helicopters and fixed-wing aircraft) are more relaxed than those for aircraft flying above that altitude and do not involve requirements for detailed flight plans.