t is the sort of operation that would horrify civil liberties campaigners in the west, but there has been little public debate in Afghanistan. Kitted out with handheld devices that contain a camera to scan eyes and an electronic pad to take fingerprints, US soldiers have been collecting huge amounts of biometric data, with little oversight from the Afghan government.
The US hopes that Hamid Karzai, the Afghan president, can be persuaded to set up a much more ambitious national biometric ID system that would hold information on every Afghan citizen from the age of 16.
Although such a move would potentially be bad news for people's privacy, it would unquestionably make life harder for insurgents.
"It allows us to understand population shifts and movements, who wasn't there before and who might be a potential threat just because they are new to that area," said Craig Osborne, the colonel in charge of Task Force Biometrics.
Already the technology, which was originally introduced in US bases in the Balkans in the early 2000s, is helping to catch dozens of wanted suspects a week. Information collected in the field is checked against a central database containing hundreds of thousands of fingerprints found by US army forensics labs on materials touched by insurgents: weapons, sticky tape from homemade bombs, and even receipts for wire transfers of money used to pay for the rebel cause.