NEW YORK - US military officials say biometrics have become a useful battlefield tool in Iraq and Afghanistan but may be facing legal and other challenges. The system that records information on people using eye scans, fingerprints and facial images is being set up by the US military in Afghanistan, The NYT reported. Sergeant Maj Haemmerle told the Times suspects can shave off their beards but that won't change their basic biometric profile. The military has already collected information on more than 1.5m Afghans, or one of every six males of fighting age, in databases operated by Nato and Afghan forces, with only occasional complaints, Times said.