Schneier on Security

Roger Lee • October 15, 2005 8:13 AM

@ Juergen

If the “suitcase full of bricks” is taken to its logical conclusion, it could make a very effective force multiplier, getting the security staff to provide considerable help to the terrorist.

Imagine, for a moment, that a terrorist decided on an attack using a chemical agent – say sarin, as used by the Aum cult on the Tokyo underground railway. Let’s further suppose that this attack is going to be staged on the London Underground, because I’m British and know it, and because recent history suggests that it is an attractive target for our very own, home-grown, terrorists. Finally let’s assume that our terrorists, unlike the Aum cult, are not expecting to survive the attack.

One of the factors that limited the casualties in Tokyo was that the cult members involved evidently didn’t want to become victims themselves, and released the sarin, apparently contained within sealed plastic bags, by prodding a hole in the bag with an umberella and running.

Let’s assume that our terrorists use a spray to create an aerosol, so dispersion will be much more efficient, and cover a much larger area.

Our terrorists decide to attack a major terminus with large underground chambers during the rush hour. Ideally our terrorists would choose a large, heavily-used, chamber with a convenient mezzanine or similar. To get the greatest effect, they ideally need the chamber to be as full as possible of stationary commuters, both to attack a lot of people, but also to overload the exits, ensuring that as many people as possible get a fatal dose.

How to arrange this? Just place a “suitcase full of bricks” at suitable locations one station along each track that the chosen chamber serves. The build up of commuters in the terminus is going to be quick and severe (choked solid within minutes, in my experience) before the station management can stop people coming in, and almost as soon as they realise they have any sort of problem, the attack takes place, not only causing many primary casualties, but also heavy secondary casualties as people get crushed and trampled as panic sets in. Finally, this type of attack would effectively deny access to the area in which it took place, hampering those trying to help said casualties.

Obviously, our authorities will have thought of this one, but how can they effectively prevent it? If you just run the trains straight through a station known to contain a suspect package, then you run the risk of delivering victims to the slaughter, as it were, and if you don’t then you run the risk of making a major contribution to an attack elsewhere. The speed at which the authorities receive and must assess the various bits of information is going to make recognising the nature of the attack in time to take countermeasures almost impossible, and certainly prone to error, which could in itself aid the terrorists, as I’ve hypothesised.

By the way, my apologies for the movie-plot scenario – Some of the times I’ve been stuck in the London Underground for extended periods have been amongst the most psychologically undermining experiences of my life, and it probably shows…