Who do you believe was responsible.
The Sahwa crowd, angry that they’re not getting a break from Maliki, accurate or not.
An AQ surge?
Shias trying to foment trouble between Sunnis and Amis?
Hard to say at this point.
As much as that area has long been a Sunni stronghold and was heavily occupied by al Qaeda for years, I haven't ruled out Iranian scum.
Iran's been sabre-rattling quite a bit of late and Iraq is one of their favorite playgrounds.