Al Qaeda's Iraqi branch claimed responsibility Nov. 10 for the triple suicide bombing attacks a day earlier against three Western hotels in Amman, Jordan. The attacks, carried out by four bombers between 8:50 p.m. and 9 p.m., killed at least 60 people and wounded more than 100. Investigators speculate the bombers used portable devices contained in either explosive belts or backpacks. The Amman attacks are the second in less than six weeks to employ smaller-scale explosive devices and target areas where civilians are most likely to congregate. On Oct. 1, suicide bombers attacked three popular restaurants on the Indonesian island of Bali, killing at least 23 people. The bombs, and those used in the July 7 London Underground bombings, also contained shrapnel to maximize casualties. All three attacks signify an evolution in militant tactics away from large and bulky explosives and toward smaller, more portable devices that can be used in a wider variety of situations. This does not mean to suggest that large vehicle-borne bombs, like those needed to bring down the Alfred P. Murrah federal building in Oklahoma City in 1995 or to destroy the U.S. Marine barracks in Beirut, Lebanon, in 1983, will never again be employed. For one thing, there still are plenty of soft targets out there with little or no protection against such assaults. As security does increase around the globe, however, militants are adapting to measures designed to stop them — and thus are staying ahead of the curve. At first glance, it would seem that the terrorist shift from large vehicle-borne improvised explosive devices (IEDs) would cause casualty counts to drop. In the case of Jemaah Islamiyah (JI) attacks in Indonesia, however, the shift to smaller devices has caused greater casualties. The August 2003 attack against the JW Marriott Hotel in Jakarta utilized a car bomb, and left 12 people dead. Likewise, the September 2004 attack against the Australian Embassy in Jakarta used vehicle-borne explosives, and killed 10 people. The use of smaller IEDs in the most recent Bali attacks killed more people than JI's last two attacks combined. The reason for the seeming discrepancy is that the rule for explosives is much like real estate — the three most important factors being location, location, location. Though a larger quantity of explosives will create a larger explosion, the impact of the explosion is determined solely by placement. If bombers can place a smaller explosive into a heavily packed crowd — such as a wedding reception or hotel lobby — it will cause more damage than a larger device that detonates farther away from its intended target. Because of the bulky nature of a vehicle compared to a backpack or a belt, it is much more difficult to maneuver into a position that will cause the most significant damage. On the other hand, a person carrying explosives in a bag or concealed under clothing is much more fluid, and can thus maneuver into the best possible position. For example, had University of Oklahoma student Joel Henry Hinrichs III entered the OU football stadium before detonating his bomb Oct. 1 — regardless of whether his was a suicide or a suicide attack — the death toll easily could have been significant. Additionally, the psychological impact of detonation in a crowded and confined area — such as a subway car — will amplify the casualty count, and also create widespread panic and confusion. Smaller explosives also are cheaper to make than larger ones — another advantage for paramilitary groups. A large IED might contain several hundred pounds of explosives and can only be used in a single location. Smaller IEDs, on the other hand, need a much smaller quantity of explosives. The backpack-style devices used in the March 2004 Madrid bombings contained about 20 pounds of explosives each. By making smaller devices, attackers can maximize their resources by creating many devices, instead of just one, with the same amount of explosives — which often are hard to procure anyway. Furthermore, having more devices allows attacks against multiple targets. The counterterrorism tactic of erecting barricades around particularly vulnerable targets — including government buildings and soft targets such as hotels — has forced militants to rethink their attack strategies, and to adapt. Instead of building bigger and bigger bombs that could possibly penetrate more secure areas, operational planners are instead thinking small — and mobile.