The Pentagon has been warning about security risks posed by social networking sites. But documents show the U.S. military uses the online sites itself to monitor and react to high-profile events.
A recent example includes the Air Force's use of Twitter, YouTube and various blogs to assess the public backlash to last spring's unannounced Air Force One flyover of the Statue of Liberty.
The Air Force also monitored public concern over the spread of swine flu.
This new Internet terrain has slippery slopes for the military. Facebook, MySpace and other social media sites are popular among service members, including those in Iraq and Afghanistan. But Pentagon officials say posting information makes it vulnerable to being lost or stolen by the enemy.