Can high technology find bin Laden?

Tracking down the West's 'most wanted' man is not going to be easy, despite access to the latest intelligence hardware, writes Owen Dyer

An American journalist recently suggested to a former Pakistani intelligence chief that Osama bin Laden's days were numbered. General Hamid Gul took savage pleasure in shooting him down. "If you can't even find the terrorists in your own country, what makes you think you can find Osama in Afghanistan?" Surprisingly, the cynical old spy's assessment echoes the pessimistic noises coming from the US intelligence community itself.

American military intelligence was designed to meet a Russian threat. Soviet society was almost impenetrable to human spies, so the US came to rely increasingly on electronic and satellite surveillance. "The Russians were ideal targets for overhead intelligence-gathering," says John Pike, a satellite expert and director of the Washington think tank, GlobalSecurity.org. "They built huge installations, and they loved to talk on the radio."

In the spy business, however, a word can be worth a thousand pictures, which explains a favourite axiom of the intelligence community: satellites can't read minds. Often the message from above cannot tell the complete story on the ground until extra intelligence is taken into account. The classic example is when US satellite pictures showed Iraqi troops moving up to the Kuwaiti border in 1990, but nothing happened in Washington until a western diplomat, driving north to Baghdad, passed columns of tanks on the road and notified the CIA.

New overhead shots were taken that convinced the agency that invasion was imminent, but they lacked human corroboration, and President Bush chose to believe his other intelligence agencies, whose contacts said Saddam was bluffing.

American spies know they should do better at recruiting foreign agents, but they do not approve of impersonating civilians and mixing in society, as the gung-ho French or Israelis do. CIA agents typically travel as accredited diplomats, eavesdropping from within their own embassies with hi-tech sensors that sweep the airwaves and phone lines of the host country.

When William Casey, Reagan's CIA director, pushed for more aggressive field operations, he was lectured by a subordinate against the James Bond mindset: it's not a question, the spy said, of finding and destroying Dr No's secret base.

Osama bin Laden is the Dr No scenario that nobody expected. Now, the spies must find and destroy him with the tools on hand. That's why they are preparing the public for a long wait. Bin Laden is not going to step out of his cave one morning, look up to the sky, and be recognised by a satellite. The imaging capabilities of these "big birds" are less impressive than most people think.

The four active optical spy satellites are essentially inverted Hubble Space Telescopes. They take black-and-white still images, at a maximum resolution of 10cm per pixel. That is insufficient to distinguish a man from a woman or a soldier from a civilian, especially since pictures can only be taken from above.

At night, most optical satellites are blind, except those with infrared cameras. The two synthetic aperture radar (SAR) satellites are unhindered by darkness or bad weather. The signal can be turned into a black-and-white picture, but the resolution is only one metre per pixel. Humans are almost invisible on this scale.

The latest development, the hyperspectral camera, can see through foliage and identify different materials such as a plywood dummy tank. The first military hyperspectral satellite was launched last month, but it is a prototype with a resolution of only 8m.

There are better civilian hyperspectral satellites, and the US is now buying up all the Afghan shots it can get from commercial imaging satellites. Some of these offer colour photos of about 1m resolution.

Commercial images are necessary because the military hardware does not offer enough coverage. The typical military spy satellite is over Afghanistan only once a day for less than five minutes. In that time, it can photograph a tiny section of the country. John Pike estimates that all the satellites now photographing Afghanistan could provide updated shots of the whole country once a week.

The photos are studied on computer screens, but at 10cm resolution, only about 150 square metres can be viewed at once. "It's like looking at the country one football pitch at a time," says Pike. It would take a montage of 30 million such pictures to show the whole of Afghanistan. The human effort involved in analysing this information is enormous, even with the help of target-recognition and change-monitoring algorithms. American intelligence agencies are now reported to be recalling retired staff to help with the task.

The other half of the satellite armoury, the signals interception birds, can't help to track down bin Laden, who switched his phone off a long time ago and relies on couriers. He may remember the case of the Chechen leader, General Dudayev, who was reportedly killed by a Russian missile that homed in on his mobile phone.

Signals satellites will help, however, in the global hunt for members of al-Qa'ida. The spacecraft form part of a listening system that permits the US to sift through the world's telecommunications almost at will. The National Security Agency always keeps recordings so they can go back into the archives with the benefit of hindsight. They are now scanning intercepts recorded before 11 September.

All civilian satellites, and most spy satellites, have orbits that are public knowledge. The Indians used this knowledge to hide preparations for their 1998 nuclear test. At HeavensAbove.com, you may easily find out when, for example, the spybird Lacrosse 3 will next be passing overhead. In the last month, this website has had more hits from Afghanistan than from any other Asian country except Japan. It may be that Osama has already figured out how to avoid the eyes in space.

He is more directly threatened by the new breed of unmanned aerial vehicles (UAVs), which fly high enough to be invisible but low enough to take good pictures. The propeller-driven Predator is crash-prone and dispensable at $4m (£3.3m) each. The jet-powered Global Hawk is also crash-prone but costs $47m.

These aircraft boast huge advantages over satellites. They can loiter overhead for hours – Global Hawk can take off on a Monday afternoon and land on Wednesday morning. Better still, they provide a moving picture to a human operator, allowing a quick response. There are only four Global Hawks, now being rushed into service ahead of schedule. The US Air Force has about 30 Predators, but most are training versions. Only seven were ready for operations in September and one of these has already gone down over Afghanistan.

The CIA has an undisclosed number of UAVs, called GNATs, which are similar to Predators. One of these UAVs is believed to have tracked a Serbian war criminal's car in Bosnia-Herzegovina and guided UN troops in to arrest him. It was a human tip-off, however, that told the agency where to send the plane in the first place.

Special Forces units carry a plethora of ground sensors that employ cameras, infrared and seismic detectors. Similar devices can be dropped from the air. Such tools could detect bin Laden if only someone knew where to put them. They face the same problem as UAVs – Afghanistan is a big country, and bin Laden is one man among many. He could simply hide in Kabul. "It's not like looking for a needle in a haystack," says Pike. "It's like looking for a piece of hay in a haystack." The Americans need a human source, and these are hard to find in Afghanistan. "Even the Russians always complained about the lack of good human assets there," says Pike. The Pakistanis claim that their Afghan sources have dried up in recent weeks. The CIA itself has had no breakthroughs in its three-year search for bin Laden, despite air-dropping books of matches that offer a $5m reward for information.

In the meantime, the Americans will have to resort to the traditional military intelligence technique: taking prisoners and interrogating them.