and Shashank Bengali

NAJAF, Iraq "" Flying banners that said "No, no to the occupation," tens of thousands of followers of the anti-American Shiite Muslim cleric Muqtada al-Sadr staged a peaceful rally Monday in one of Iraq's holiest cities, where they burned American and Israeli flags and called for U.S. troops to leave Iraq.

But there were ominous signs afterward that al-Sadr's enormous Mahdi Army militia may be preparing for renewed violence in Baghdad.

Monday evening, as protesters returned in trucks and buses to Baghdad's sprawling Shiite slum of Sadr City, a McClatchy Newspapers reporter saw men in several buses carrying pistols and AK-47s, a violation of new security laws. One man who identified himself as a Mahdi Army member bragged that weapons were being taken from Najaf to Baghdad hidden in truck beds.

The protest in Najaf, which al-Sadr had called as a gesture of national unity, took place under heavy Iraqi security on the fourth anniversary of the fall of Saddam Hussein's regime. Protesters waving red, white and black Iraqi flags marched about five miles from a mosque in the town of Kufa to Najaf, 100 miles south of Baghdad.

Although the Mahdi Army is blamed for the widespread kidnapping and killing of Sunni Muslims, over the weekend al-Sadr urged Iraqi security forces and all Iraqi people to band together against U.S.-led coalition forces.

The rhetoric at the rally was menacing at times. "The occupation and the people connected to it will vanish," the demonstration's organizers said in a statement, "and Iraq will stay for Iraqis and the country for its sons."

Much of the country was quiet Monday after a last-minute government decree made it a national holiday. Vehicles were barred from the streets of Baghdad for 24 hours, until 5 a.m. Tuesday.

At the protest, the message of unity appeared to prevail. Although the march culminated in Najaf's al-Sadrain Square "" which honors al-Sadr's late father and uncle, both revered Shiite clerics "" protesters didn't carry pictures of al-Sadr or other religious leaders. Instead, the Iraqi flag was seen everywhere.

"It's a spiritual duty for each Iraqi to go out and demand the departure of the occupation," said Hamid Kahil, an al-Sadr supporter who traveled to Najaf from Nasiriyah, about 150 miles to the south.

"We will demonstrate and demonstrate," he said, "and if the demonstration doesn't work, there will be other ways to force the occupation to leave our beloved country."

The vast majority of the demonstrators were Shiites, but some Sunnis from Iraq's southern Basra province also participated. "Our project is a national one," said Omar Abdul Sattar, a spokesman for the Iraqi Islamic Party, the leading Sunni political party.

There was no appearance by al-Sadr, who hasn't been seen publicly since a U.S.-Iraqi security crackdown against the Mahdi Army and Sunni insurgents started seven weeks ago. Some analysts speculated that the protest, which was announced two weeks ago, was Sadr's attempt to reassert influence over his followers.

(The march began at about 8:30 a.m. in the neighboring town of Kufa, a popular pilgrimage site for Shiites, and proceeded southwest to Najaf. Iraqi flags flew from balconies, public parks and government buildings in Najaf, the site of the tomb of Imam Ali "" whom Shiites consider the rightful successor to the Prophet Muhammad "" and one of the world's holiest cities for Shiites.

"Iraqi flags are evidence of Iraqis' unity, their pride in their country and their rejection of the occupation," said Nassar al-Rubaie, the head of Sadr's legislative bloc, who took part in the march.

Lt. Col. Chris Garver, a U.S. military spokesman, said the fact that the march was peaceful was a good sign, four years after Saddam's removal.

"We think that the right to express yourself is an inherent right in democracies," Garver said. "We acknowledge that some people have different opinions, and they're expressing them through nonviolent means."

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