Apparently, the attack appears to be either a planted bomb or a suicide bomber, and not a rocket as initially thought.
A day after the attack, a message posted on a website by Ansar al-Sunna provided details of the strike. According to the message, the suicide bomber was a 24-year-old man from Mosul who worked at the base for two months, and who has provided the group detailed information about the base. One soldier I know thinks that the bomber is likely to be an Iraqi policeman, although it could be a member of the Iraqi national guard. Only the Iraqi police and national guard troops are allowed in the mess tents with US soldiers, apparently.
Maybe some of the soldiers over there can correct me on my assumptions, but this is my take on it -- expect similar attacks followed by a backlash of some sort soon, as the DoD trips over themselves to address the latest crisis. The level of anger and paranoia kicked up during the process of securing U.S. bases against "Iraqi allies" could become dangerous, as it could threaten to burn important bridges between U.S. forces and the Iraqi police and national guard troops. Let's hope that calmness and professionalism prevails.
This wasn't just a bomb. It was a wedge.