Coalition troops launched Operation Shank in Ramadi Friday, a day after insurgents in that city were videotaped walking the streets and firing mortar rounds.

Approximately 200 Iraqi Army soldiers, along with 300 Marines from 3rd Battalion, 7th Marine Regiment, deployed to Ramadi, 70 miles west of Baghdad, to begin conducting combined clearing operations intended to disrupt the insurgency and set the conditions for successful elections on Dec. 15.

On Thursday, the U.S. military played down reports by residents and police of armed insurgents walking the streets and of widespread attacks against American and Iraqi targets in the city. The military said only one rocket-propelled grenade was fired at an observation post, causing no casualties. News agencies did run videotape allegedly shot in Ramadi, the capital of Anbar province, that showed armed insurgents distributing Al Qaeda leaflets and firing mortar rounds.

Maj. Gen. Rick Lynch, a coalition operations officer, warned that Al Qaeda in Iraq, led by Jordanian terror mastermind Abu Musab al-Zarqawi, would probably step up attacks in Ramadi and elsewhere in Iraq in the next two weeks to try to disrupt parliamentary elections on Dec. 15.

In Baghdad, hundreds of Shiite and Sunni Muslims prayed together Friday, then staged a joint demonstration to denounce military and police raids and the widespread arrests of suspected insurgents. The show of unity comes ahead of potentially divisive parliamentary elections.

Men waving Iraqi flags and women dressed in black robes carried posters of their missing sons. Some protesters held up portraits of Sunni clerics who have been killed since the U.S. invasion in 2003.

Shiites make up the majority in Iraq, but were oppressed by former ruler Saddam Hussein, who is a Sunni. Since Saddam's overthrow, Shiites have controlled most of the political power in Iraq, while the anti-U.S. insurgency has been dominated by Sunnis.

Sunni homicide bombers have targeted Shiite mosques and gatherings.

Sunni leaders have complained of attacks by Shiite death squads tied to the government. Last month, U.S. troops discovered an interior ministry jail with 173 detainees, some showing signs of torture.

The ministry is "killing our sons at the orders of the [Iranians]," one poster read, referring to alleged ties between Interior Minister Bayn Jabr and Iran. Another poster referred to Jabr as an American agent.

The U.S. military said the number of car bombings detonated remotely declined to 68 in November from 130 in February. However, suicide attacks have not consistently decreased over the past year. After more than 70 such attacks in May, the number fell in August by nearly half and then climbed to over 50 two months later.