About 5,000 U.S. Marines, British troops and Iraqi commandos launched a new offensive Tuesday called Operation Plymouth Rock in an effort to quash enemy forces in terror hotbeds south of Baghdad.

The operation kicked off with early morning raids in the town of Jabella (search) in Babil province, netting 32 suspected insurgents, the U.S. military said in a statement. U.S. and Iraqi forces were conducting house-to-house searches and vehicle checkpoints. Jabella is 50 miles south of Baghdad.

In other joint raids conducted in Iskandariyah and Latifiyah, another 45 suspected terrorists were arrested, said Iraqi police Capt. Hadi Hatif.

The new offensive was the third large-scale military assault this month aimed at suppressing Iraq's persistent insurgency ahead of crucial elections set for Jan. 30. Much of the focus this far has been in the Sunni Triangle city of Fallujah.

"For democracy to succeed, areas of the country cannot remain in the control of insurgents," Defense Secretary Donald Rumsfeld told reporters at the Pentagon on Tuesday, adding that Fallujah is being freed from the "murderous enemies of progress."

"Operations in Fallujah and elsewhere demonstrate anew the extremism of those opposing Iraqi democracy," Rumsfeld continued. "History has shown ... that when people are given a chance to rule their own lives they seize it, and why should we believe the people in Iraq would think any differently?"

In other violence, masked gunmen assassinated a Sunni (search) cleric north of Baghdad — the second such killing in as many days — and insurgents hit a U.S. convoy with a roadside bomb near the central Iraqi city of Samarra, prompting the Americans to open fire, killing an Iraqi, hospital officials said.

The region of dusty, small towns south of the capital has become known as the "triangle of death" for the frequent attacks by car bombs, rockets and small arms on U.S. and Iraqi forces there and for frequent ambushes on travelers.

The military said violence has surged in the area in recent weeks in an apparent attempt to divert attention away from the U.S. assault on Fallujah (search).

In the past three weeks, Iraqi troops and Marines have detained nearly 250 insurgents, the statement said.

"Fallujah is no longer a terrorist stronghold," Gen. Richard Myers, chairman of the Joint Chiefs of Staff, told reporters during the press conference with Rumsfeld on Tuesday, noting that insurgents likely will continue to employ inhumane and brutal tactics to derail the Jan. 30 elections.

And "there's absolutely no doubt in my mind that Iraqis ... realize the importance and their role and their mission" in making sure Iraq is put on the way toward democracy, Myers added.

They have been aided by British forces from the 1st Battalion of the Black Watch Regiment, who were brought to the area from southern Basra to aid U.S. forces in closing off militant escape routes between Baghdad, Babil province to the south and Anbar province to the west.

Fallujah Fighters May Have Scattered

The massive Fallujah invasion — involving some 10,000 U.S. and Iraqi troops — has left the former guerrilla stronghold mostly in U.S. hands, though fighting with pockets of gunmen has been going on for days, the military has said.

In the wake of the massive assault on the rebel bastion, insurgent attacks throughout central and northern Iraq stepped up dramatically. Earlier this month, northern Mosul witnessed a mass insurgent uprising in apparent support of Fallujah's guerrillas. Some 2,400 U.S. and Iraqi troops were sent in to retake control over western parts of the city.

At least 54 U.S. troops have been killed and 425 wounded during the Fallujah offensive that began Nov. 8. Throughout Iraq, the number of American soldiers wounded overall has surpassed 850, and the wounded total for the entire war has topped 9,000, the Pentagon said Tuesday.

"We believe some fighters from Fallujah skirted away and came down to our area to, among other reasons, take a little bit of pressure off of Fallujah. To what degree that was coordinated and how extensive, we really can't say," said Capt. David Nevers, a spokesman for the 24th Marine Expeditionary Unit.

Another reason for the spike in attacks might also be that Iraqi troops and Marines have stepped up house-to-house searches and vehicle checkpoints in the area for the last three months, detaining nearly 250 insurgents, he said.

"For the last couple months, we've gone into areas that had formerly not seen a lot of presence ... We went in and stirred up a few hornets' nests," Nevers said.

The slain Sunni cleric, Sheik Ghalib Ali al-Zuhairi, was shot as he left a mosque in the town of Muqdadiyah, 60 miles north of Baghdad, said police Col. Raisan Hussein.

Al-Zuhairi was a member of the Association of Muslim Scholars, an influential group that has called for a boycott of nationwide elections.

A day earlier, gunmen assassinated another prominent Sunni cleric in the northern city of Mosul — Sheik Faidh Mohamed Amin al-Faidhi, who was the brother of the group's spokesman. It was unclear whether the two attacks were related.

Al-Sadr Aid: Gov't Violated Najaf Deal

Meanwhile, a top aide to radical Shiite cleric Muqtada al-Sadr (search) accused the government of violating terms of the August agreement that ended an uprising by al-Sadr's followers in Najaf.

Ali Smeisim, al-Sadr's top political adviser, made no explicit threats as he leveled his allegations at a Baghdad news conference. But his remarks raised the possibility of a new confrontation between the government and al-Sadr's Mahdi Army (search) militia, which rose up against the Americans and their Iraqi allies in April and August.

Smeisim said the government has broken a promise in the August agreement not to arrest members of al-Sadr's movement and to release most of them from detention.

"The government, however, started pursuing them and their numbers in prisons have doubled," Smeisim said. "Iraqi police arrested 160 al-Sadr loyalists in Najaf four days ago."

Smeisim also accused the government of conspiring with two major Shiite parties, Dawa and the Supreme Council for the Islamic Revolution in Iraq, to marginalize al-Sadr's movement and prevent its clerics from speaking in mosques.

Trouble from al-Sadr's armed followers would further complicate the security situation ahead of the January vote.

The United States is eager for the election to go ahead as planned, hoping that an elected government widely accepted by the Iraqi people will take the steam out of the insurgency still raging in Sunni areas of central, western and northern Iraq as well as the capital.

But a boycott by Sunni Arabs — who make up an estimated 20 percent of the nearly 26 million population — could deprive the new government of legitimacy. The majority Shiites, believed to form 60 percent of the population, strongly support elections.

Still, Iraq's interim prime minister expressed confidence Monday that the election will succeed. Ayad Allawi said he believed that only "a very small minority" would abstain during the election.

As the election approaches, U.S. commanders in Iraq probably will expand their troops by several thousand. Army units slated to depart are also being held back until after the election. There are now about 138,000 U.S. troops in Iraq.

"I think generally, we're on track with where we want to be" in regards to how many American troops are posted in Iraq, Myers told reporters Tuesday.

Myers added that despite reports that the Iraqi security forces aren't yet adequate enough to man elections themselves, they are "gaining confidence."

In Egypt, where 20 nations have gathered for an international conference on Iraq, members have committed themselves to supporting the U.S.-backed Iraqi interim government and its war against insurgents.

The gathering, which included many who had opposed the war, represented hard-won acknowledgment of the need for international cooperation to deal with its consequences.

In other developments:

— In northern Kirkuk, an ethnic Kurdish contractor who worked with U.S. forces was kidnapped from his home by gunmen, police said.

— A gunbattle between police and rebels south of Baghdad in the central Iraqi town of Mahaweel left one fighter dead, police said.

— The U.S. Embassy said Monday that a bomb was discovered on a commercial flight inside Iraq. No further details were released and the statement did not say whether the affected flight had arrived or was preparing to depart. Aircraft flying into and out of Baghdad have been fired on frequently by insurgents.

— The first independent aid convoy to enter Fallujah had to turn back before delivering any assistance because of security concerns, the Red Cross said Tuesday.

The Associated Press contributed to this report.