Deaths from revenge killings now exceed those from terrorist or anti-government activity. Al Qaeda is beaten, and running for cover. The Sunni Arab groups that financed thousands of attacks against the government and coalition groups, are now battling each other, al Qaeda, and Shia death squads. It's not civil war, for there are no battles or grand strategies at play. It's not ethnic cleansing, yet, although many Sunni Arabs are, and have, fled the country. What's happening here is payback. Outsiders tend to forget that, for over three decades, a brutal Sunni Arab dictatorship killed hundreds of thousands of Kurds and Shia Arabs. The surviving victims, and the families of those who did not survive, want revenge. They want payback. And even those Kurds Shia Arabs who don't personally want revenge, are inclined to tolerate some payback. Since the Sunni Arabs comprise only about 20 percent of the population, and no longer control the police or military, they are in a vulnerable position.
After Saddam's government was ousted three years ago, the Sunni Arabs still had lots of cash, weapons, and terrorist skills. Running a police state is basically all about terrorizing people into accepting your rule. For the last three years, the Sunni Arabs thought they could terrorize their way back into power. Didn't work.