You first heard about it on Stak Attack back in March:

Now it’s underway.

About 10,000 U.S. soldiers launched an offensive against al-Qaida in Iraq northeast of Baghdad early Tuesday, killing at least 22 insurgents, the U.S. military said.

The raids, dubbed “Operation Arrowhead Ripper,” took place in Baqouba, the capital of Diyala province, and involved air assaults under the cover of darkness, the military said in a statement. The operation was still in its opening stages, it said.

On Monday, military officials said U.S. and Iraqi forces had launched attacks on Baghdad’s northern and southern flanks to clear out Sunni insurgents, al-Qaida fighters and Shiite militiamen who had fled the capital and Anbar during a four-month-old security operation.

A top U.S. military official said American forces were taking advantage of the arrival of the final brigade of 30,000 additional U.S. troops to open concerted attacks.

“We are going into the areas that have been sanctuaries of al-Qaida and other extremists to take them on and weed them out, to help get the areas clear and to really take on al-Qaida,” the senior official said on condition of anonymity because he was not authorized to speak about the operation. “Those are areas in the belts around Baghdad, some parts in Anbar province and specifically Diyala province.”

Pronouncements that the surge isn’t working may have been premature.

Update (AP): Meanwhile, in Baghdad, a truck bomb destroys a Shiite mosque and kills 75. As the Times notes, the reason for the Diyala offensive is to stop the sectarian violence by shutting off AQ’s supply of car bombs; the mosque bombing presumably is their reply. If you missed them in April, you’ll absolutely want to revisit these hair-raising Times and WaPo reports, published coincidentally on the same day, on the depth of jihadi entrenchment in Baquba, where the offensive’s begun. The city’s a witch’s brew of “former members of the Saddam Hussein army and paramilitary forces, the Fedayeen; angry and impoverished Sunni men; criminal gangs; Wahhabi Islamists; and foreigners,” writes the Times, suggesting that this may well end up being the nastiest battle of the war. Michael Yon frames the battlefield:

They are ready for us. Giant bombs are buried in the roads. Snipers—real snipers—have chiseled holes in walls so that they can shoot not from roofs or windows, but from deep inside buildings, where we cannot see the flash or hear the shots. They will shoot for our faces and necks. Car bombs are already assembled. Suicide vests are prepared.

Read his whole post, as the conventional analogy here is to the Battle of Fallujah in 2004 and he argues that in fact it was that battle that helped lead us to this point by giving AQ a disgruntled population to shelter them.

We’re taking it to the Mahdi Army now too, although yesterday’s action seems less an organized offensive than a skirmish.