Scanners, Sensors are Wrong Way to Secure the Subway

We'll spend millions on new technology, and terrorists will just adapt

By Bruce Schneier
Daily News
April 7, 2010

People intent on preventing a Moscow-style terrorist attack against the New York subway system are proposing a range of expensive new underground security measures, some temporary and some permanent.

They should save their money -- and instead invest every penny they're considering pouring into new technologies into intelligence and old-fashioned policing.

Intensifying security at specific stations only works against terrorists who aren't smart enough to move to another station. Cameras are useful only if all the stars align: The terrorists happen to walk into the frame, the video feeds are being watched in real time and the police can respond quickly enough to be effective. They're much more useful after an attack, to figure out who pulled it off.

Installing biological and chemical detectors requires similarly implausible luck -- plus a terrorist plot that includes the specific biological or chemical agent that is being detected.

What all these misguided reactions have in common is that they're based on "movie-plot threats": overly specific attack scenarios. They fill our imagination vividly, in full color with rich detail. Before long, we're envisioning an entire story line, with or without Bruce Willis saving the day. And we're scared.

It's not that movie-plot threats are not worth worrying about. It's that each one -- Moscow's subway attack, the bombing of the Oklahoma City federal building, etc. -- is too specific. These threats are infinite, and the bad guys can easily switch among them.

New York has thousands of possible targets, and there are dozens of possible tactics. Implementing security against movie-plot threats is only effective if we correctly guess which specific threat to protect against. That's unlikely.

A far better strategy is to spend our limited counterterrorism resources on investigation and intelligence -- and on emergency response. These measures don't hinge on any specific threat; they don't require us to guess the tactic or target correctly. They're effective in a variety of circumstances, even nonterrorist ones.

The result may not be flashy or outwardly reassuring -- as are pricey new scanners in airports. But the strategy will save more lives.

The 2006 arrest of the liquid bombers -- who wanted to detonate liquid explosives to be brought onboard airliners traveling from England to North America -- serves as an excellent example. The plotters were arrested in their London apartments, and their attack was foiled before they ever got to the airport.

It didn't matter if they were using liquids or solids or gases. It didn't even matter if they were targeting airports or shopping malls or theaters. It was a straightforward, although hardly simple, matter of following leads.

Gimmicky security measures are tempting -- but they're distractions we can't afford. The Christmas Day bomber chose his tactic because it would circumvent last year's security measures, and the next attacker will choose his tactic -- and target -- according to similar criteria. Spend money on cameras and guards in the subways, and the terrorists will simply modify their plot to render those countermeasures ineffective.

Humans are a species of storytellers, and the Moscow story has obvious parallels in New York. When we read the word "subway," we can't help but think about the system we use every day. This is a natural response, but it doesn't make for good public policy. We'd all be safer if we rose above the simple parallels and the need to calm our fears with expensive and seductive new technologies -- and countered the threat the smart way.

earlier essay: Google And Facebook's Privacy Illusion
later essay: The Meaning of Trust
categories: Terrorism
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Photo of Bruce Schneier by Per Ervland.

Schneier on Security is a personal website. Opinions expressed are not necessarily those of Co3 Systems, Inc..