CAIRO — The first online statement from the new leader of al-Qaida's affiliate in Iraq claims that the militant network is returning to strongholds from which it was driven by U.S. forces and their Sunni allies before the American withdrawal at the end of last year.

The al-Qaida leader claimed the militant group is preparing operations to free prisoners and assassinate court officials.

The audio identified the speaker as Abu Bakr al-Baghdadi, who became head of the Islamic State of Iraq in 2010. It was posted late Saturday on a website regularly used by the militant movement to make statements.

Al-Baghdadi warned the United States that it would soon suffer militant attacks on its territory.

He also invited Muslims to come to Iraq to join his militants.

The statement comes as Sunni insurgents, now believed to be dominated by the ISI, step up attacks against Shiites, government officials and other targets, in what is seen as a bit to undercut the authority of Iraq's government and revive sectarian conflict.

"I bring you good news: We are starting a new phase in our struggle with a plan we named 'Breaking the walls,' and we remind you of your priority to free the Muslim prisoners," he said.

"At the top of your priorities regarding targets is to chase and liquidate the judges, the investigators and the guards," he said.

He urged tribal leaders to send their men to join al-Qaida as it returns to areas from which it withdrew — a reference to reverses the ISI suffered at the hands of U.S. forces and allied Sunni militias in 2007 and 2008.

"I urge you to send your sons to join the ranks of the mujahideen (fighters) in defense of your religion and honor," he said. "The majority of the Sunnis in Iraq support al-Qaida and are waiting for its return."

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Deadliest day in 2 years

BAGHDAD — A startling spasm of violence shook more than a dozen Iraqi cities Monday, killing over 100 people in coordinated bombings and shootings and wounding twice as many in the country's deadliest day in more than two years.

With the U.S. military gone and the government mired in infighting, the Iraqi wing of al-Qaida has vowed to push the nation toward civil war.

— Associated Press