Counter-terrorism experts have drawn up plans to develop an array of advanced technologies capable of spotting would-be terrorists in a crowd before they have time to strike.
Scientists and engineers have been asked to devise ways of analysing people's behaviour and physiology from afar, in the hope they may reveal clues about their mental state and even their future intentions.
Under Project Hostile Intent, scientists will aim to build devices that can pick up tell-tale signs of hostile intent or deception from people's heart rates, perspiration and tiny shifts in facial expressions.
The project was launched by the US department of homeland security with a call to security companies and government laboratories for assistance.
According to the timetable set out, the new devices are expected to be trialled at a handful of airports, borders and ports of entry by 2012.
The plans describe how systems based on video cameras, laserlight, infra-red, audio recordings and eye tracking technology are expected to scour crowds looking for unusual behaviour, with the aim of identifying people who should be approached and quizzed by security staff, New Scientist magazine reports.
The project hopes to advance a security system already employed by the US transportation security administration that monitors people for unintentional facial twitches, called "micro-expressions", that can suggest someone is lying or trying to conceal information.
Studies by Paul Ekman, a psychologist at the University of California, San Francisco, have revealed that involuntary expressions can often betray someone's true intentions. If you flash your teeth, lower your eyebrows and wrinkle your nose for a fraction of a second while trying to smile, you have just demonstrated the micro-expression for disgust.
A major hurdle will be developing technology that can make correct decisions quickly. "Right now, screeners have typically less than one minute to examine a traveller's documents and assess whether they are a threat," said Larry Orluskie, of the department of homeland security.
The project is also expected to investigate developing a lie detector-type test that can be used remotely - an advantage because it would not interfere with the flow of a crowd and it could be used without the target's knowledge.
Experts yesterday were sceptical that today's technology will be able to predict hostile intent accurately enough to be useful. Dr Ekman said a terrorist might confound security measures by showing a range of expressions from fear of being caught to distress at the possibility of dying. "I don't know. No one knows," he told New Scientist.
Anthony Richards, a counter-terrorism expert at St Andrews University who has worked on Britain's ability to pre-empt a major terrorist attack, agreed that the project faced substantial hurdles.
"There could be all kinds of reasons that might make people behave in certain ways that have nothing to do with terrorism. If you have heightened security and there are a lot of police around, it could be possible that you can feel and look guilty even when you haven't done anything wrong.
"We need to reduce the motivation for people doing these kinds of things. We shouldn't just accept that terrorism will remain as it is or worsen over the next 20 or 30 years and then just put all the technological solutions in place. Technology is certainly important in the fight against terrorism but that shouldn't detract from the crucially important challenge of finding out what is driving terrorism. We need to have a sensible and honest appraisal as to what is radicalising young people."
Peter McOwan, a computer scientist who is developing sensors to detect people's moods at Queen Mary, University of London, said: "It's just like something from Minority Report. They have been watching too many Tom Cruise movies."
RIP America.
