BAGHDAD, Iraq – Thousands of U.S.-led forces on Wednesday squeezed insurgent strongholds in the dusty lawless towns south of Baghdad, as the purported voice of Iraq’s most-wanted terrorist blasted Muslim clerics for failing to rally behind the anti-U.S. uprising.

The large-scale military offensive – the third in Iraq this month – unfolded with more than 5,000 U.S., British and Iraqi troops hunting for Sunni Muslim insurgents in what a military spokesman described as a series of “precision” raids.

“This is not a Fallujahlike mass assault,” Capt. David Nevers, a spokesman with the 24th Marine Expeditionary Unit, wrote in an e-mail, referring to the huge U.S.-led attack earlier this month on the town west of Baghdad. “The environment here south of Baghdad is very different, requiring a different approach.”

Nevers said the latest offensive is “surgical rather than sweeping in nature” and that gunmen who fled Fallujah to that region would not find safety.

The offensive, dubbed Operation Plymouth Rock to mark the Thanksgiving holiday, is using what Nevers described as “growing intelligence” to capture insurgents. He did not know how many arrests it had yielded.

The raids focused on the towns along the east bank of the Euphrates River, 50 miles south of Baghdad, in an area infested with insurgents and criminals. In one of the towns, Latifiyah, police are afraid to come out of their barracks. The region, known as the “triangle of death,” is viewed as a launching pad for attacks on Baghdad.