Random Security: LAX's ARMOR System

Security officials at Los Angeles International Airport now have a new weapon in their fight against terrorism: randomness. Anxious to thwart future terror attacks in the early stages while plotters are casing the airport, security patrols have begun using a computer program called ARMOR (Assistant for Randomized Monitoring of Routes) to make the placement of security checkpoints completely unpredictable. Now all airport security officials have to do is press a button labeled RANDOMIZE, and they can throw a sort of digital cloak of invisibility over where they place the cops' antiterror checkpoints on any given day.

Developed by computer scientists at the University of Southern California, ARMOR aims to thwart terror plots during the surveillance phase. A plot typically starts "18 months to four years prior to an attack," when terrorists begin watching for security weaknesses, says James Butts, deputy executive director of law enforcement at Los Angeles World Airports, which runs LAX. "We're trying to block the surveillance cycle" by making patrols less predictable.

Randomness isn't easy. Even when they want to be unpredictable, people follow patterns. That's why the folks at LAX turned to the computer scientists at USC.

The idea began as an academic question in game theory: how do you find a way for one "agent" (or robot or company) to react to an adversary who has perfect information about the agent's decisions? Using artificial intelligence and game theory, researchers wrote a set of algorithms to randomize the actions of the first agent. Academic colleagues couldn't appreciate how the technology could be useful. "It was very disappointing," says Milind Tambe, the USC engineering professor who led the ARMOR team.

LAX officials, under a mandate from the mayor to improve airport security, latched onto the idea. During the summer, grad students fed reams of classified data about the airport's facilities into the program, and ARMOR started running in August, says Butts.

Soon ARMOR will begin jumbling the placement of the bomb-sniffing canine patrols, says Butts. Other potential uses are too secret to talk about. The new random placement "makes travelers safer" and even gives them "a greater feeling of police presence" by making the cops appear more numerous, says Butts. That's good for visitors and, officials hope, bad for would-be terrorists.