By focusing on planes, terrorists take a calculated risk

On Christmas Day, Umar Farouk Abdulmutallab allegedly attempted to blow up a Northwest Airlines flight from Amsterdam to Detroit with plastic explosives hidden in his underwear. On Dec. 22, 2001, Richard Reid tried to blow up a transatlantic flight with explosives hidden in his shoes. Incompetent and poorly supported, they were quickly foiled by passengers and flight crew. But the fact that Abdulmutallab would try a variation of Reid’s attack eight years later raises some interesting questions about terrorist tactics.

One question in particular is, why airplanes? Anyone who has traveled on a train, subway, bus or ferry in the United States knows that anyone can board without much fear of being detained or searched.

Meanwhile, other terrorists have developed a brutally simple tactic, just opening fire with automatic weapons in crowded areas. The 10 terrorists in the 2008 Mumbai attacks claimed more than 170 victims, and Army Maj. Nidal Malik Hasan is charged with killing 13 people at Ft. Hood, Texas, in November.

Since Sept. 11, 2001, security surrounding U.S. airplanes has become tighter and tighter, yet terrorists still target planes, even if this means that their attacks are more likely to be thwarted. Why do terrorists continue to target airplanes when other transportation systems are less heavily secured and other modes of attack have proved successful?

Targeting civilian aircraft still makes sense, from the terrorists’ point of view, for at least five reasons.

First, nature is working with them. People don’t naturally fly 30,000 feet above the ground at 300 mph; it takes a very special machine. These machines are much more vulnerable than trains or ships. One person can easily carry enough explosives to blow a hole in the side of a pressurized aircraft, which may be enough to bring it down and kill everyone aboard. The same explosive on a train or ship would likely only cause minor damage.

Second, the costs of reduced air travel, or slower air travel, are borne by business travelers and those with money -- exactly those people who are most likely to influence policymakers and government decisions. Terrorists aren’t attacking for the fun of it; they want to have an impact on government policy, and the way to do that is to target those who have clout.

Third, it is difficult for these travelers to switch to another mode of transportation, given the distances involved. Much as the folks at Cunard might wish otherwise, almost no amount of terrorism is going to persuade most people to take a passenger ship across the Atlantic for seven days rather than fly in seven hours. This means that demand for air travel is inelastic; travelers have little option but to bear the costs of increasing security, lost time and risks.

Fourth, people are already afraid of flying. Despite statistics showing that flying is safer than driving, people are still more afraid of hurtling through the air in a large aluminum tube than sliding behind the wheel for a trip to the grocery store. It’s easy to play on these fears, even with incompetent attacks that fail.

Finally, our political system is structured to overreact to attacks on aircraft and to underreact to other kinds of attacks, particularly shooting sprees. In reaction to the “shoe bomber,” we now all take off our shoes at security checkpoints. Because of the “underwear bomber,” we now may be subject to thorough body scans before boarding a flight. The 2006 plot to blow up seven transatlantic flights out of London cursed us with the inability to bring a bottle of water on board.

Security agencies feel duty-bound to do something, and politicians wring their hands about whether they are doing enough. In comparison, there appears to be no limit to the number of fatalities that can be inflicted by automatic weapons fire in the United States without generating a political reaction. Politicians limit themselves to expressions of sorrow for the victims and the families, and then the matter is quietly dropped.

One might think this provides an opportunity for Al Qaeda to easily kill large numbers of Americans, but that misses the point of terrorism. Killing large numbers in a way that is quickly forgotten is much less useful than killing a few or even none in a way that causes profound ripples of fear and costly overreactions on the part of the target group. Al Qaeda has no need to organize gun rampages against Americans if the occasional low-budget aircraft attack does the trick.

Andrew H. Kydd is an associate professor of political science at the University of Wisconsin, Madison. Barbara F. Walter is a professor of political science at UC San Diego’s Graduate School of International Relations and Pacific Studies. They are the authors of “Strategies of Terrorism.”