Safety in the Skies: Malcolm Gladwell, on target.

The better we are at preventing and solving the crimes before us, the more audacious criminals become. Put alarms and improved locks on cars, and criminals turn to the more dangerous sport of carjacking. Put guards and bulletproof screens in banks, and bank robbery gets taken over by high-tech hackers. In the face of resistance, crime falls in frequency but rises in severity, and few events better illustrate this tradeoff than the hijackings of September 11th. The way in which those four planes were commandeered that Tuesday did not simply reflect a failure of our security measures; it reflected their success. When you get very good at cracking down on ordinary hijacking — when you lock the stairs at the back of the aircraft with a Cooper Vane — what you are left with is extraordinary hijacking.

New Yorker via gladwell.com [thanks, David]