Defense officials say they've identified an unlikely new threat to national security- Facebook. A new list of rules aims to prevent soldiers and Defense Ministry employees from revealing classified information on social networking sites. The officials say some soldiers have uploaded pictures of themselves with classified equipment and inadvertently revealed sensitive information. The rules released Thursday allow soldiers to create pages on networking sites as long as they don't identify themselves as soldiers or reveal any information about what they do. The officials say defense authorities continue to surf the Net to make sure there are no further security breaches. They spoke on condition of anonymity because the rules have not been officially published.