New Threat Renews Old Tactic

 Editor’s note: On Thursday in New York City, officials announced they had received the first specific and credible—if still unconfirmed—threat against the subway system. The information, according to at least one source, was that 19 attackers planned to place improvised explosive devices, or IEDs, on trains. The city had just emerged from a state of heightened alert for the Jewish holiday of Rosh Hashana, with Yom Kippur to follow next week, and with the beginning of the Muslim holiday of Ramadan.

At an afternoon press conference, Mayor Mike Bloomberg promised an increased police presence throughout the system, reported Newsday:

"We have done and will continue to do everything we can to protect this city," Bloomberg said, adding that he planned to take the subway home Thursday night. "We will spare no resource, we will spare no expense. We have increased our police presence on our subways."

Let's play a game. You be New York City, and I'll be the terrorist.

You don't know when or how I'll strike. You also don't know what or where I'll attack—subways seem like my new target of choice, but they could be just a passing fad. You know that I want to kill people, but you don't know how many, because to me sowing fear might be as important as taking lives. And you don't know whether I'm willing to sacrifice my life in order to take others'. A burglar wants loot, a rapist wants control but what I want is a little fuzzy—so predicting my next move is a dice roll.

I'm not your only problem. There are also my potential victims, the people who live and work in New York City. You've got to protect them while making sure that you don't cause more disruption than my potential attack. You've got to convince people that they are being protected, without scaring them so much that their anxiety shuts down the city.

Events like 9-11 or the London bombings are human dramas, but the policy choices they force are supposed to be cold calculations about the game that killers and protectors play, the costs they bear, and the chances they take.

Last week the New York Police Department began random searches of passengers' bags on subways, buses, and commuter trains. Officers aren't targeting every bag and—according to Police Commissioner Ray Kelly—won't use any profile to target particular subway riders. That means the cops are taking a chance that they will search enough bags to catch a bomber—if there is a bomber—before one strikes, or at least dissuade him from trying to get through the turnstiles.

It's a shot in the dark, but so is the terrorists' mission, says Columbia business professor Geoffrey Heal. "There's a lot of chance in it. Presumably they don't know which train they're going to get on, what car they're going to get on, how many people will be in it," he tells the Voice. "All of this is decided at the last minute."

Heal's expertise on terrorism concerns the choices that governments make to defend against the threat of random violence. In this calculus of security, there are certain givens, says Heal. One is that suicide bombings are easy to pull off as long as you've got volunteers. "The first few times it happens," he adds, "it's virtually impossible to stop."

The surest way to protect the subway system from bombs would be to screen every passenger's bag. But that would not only be enormously expensive in terms of time and manpower, it could have a human cost. The subways would become very inconvenient to ride, more people would drive cars, and there'd be more fatal road accidents. That's not to mention that the long lines of riders waiting to get screened would pose a tempting target.