The United States has begun building a new Iraqi army by deploying some of the nation's exiles and internal dissidents around the country, while using its own might to weaken Saddam Hussein's grip on power inside Baghdad.

Early Monday, an armored column roared into the heart of the Iraqi capital and U.S. forces raided one of Saddam's key palaces.

Senior defense officials said the assault, the third in three days, was designed to be another show of force to demonstrate to Iraqis that invading troops can go where they want. They said it wasn't an effort to occupy the city.

Americans might stay a bit longer than their earlier incursions into the city over the weekend, but the occupations will last hours, not days, one official said.

Several hundred soldiers of the Iraqi National Congress exile group were flown to an area near the city of Nasiriyah, the group said Sunday.

"These are Iraqi citizens who want to fight for a free Iraq, who will become basically the core of the new Iraqi army once Iraq is free," said Marine Gen. Peter Pace, vice chairman of the joint chiefs of staff.

More will be deployed to other southern cities, while another group would work with invasion forces in the north, a senior Pentagon official said Sunday on condition of anonymity. Officials declined to say how many would be involved but said the number would grow in coming days.

The group sent to the south was mostly Shiites who had taken refuge in the north, one official said. Forces working in the north will be Kurdish. Uprisings by Shiites and Kurds were crushed by Saddam in 1991.

The troops flown into Nasiriyah will help with the distribution of humanitarian aid, keep order and "root out pro-Saddam elements" such as militia from the Fedayeen, Saddam's Ba'ath Party and others who have put up stiff resistance to coalition forces and prevented other Iraqi fighters from surrendering, said Riva Levinson, a consultant and INC spokeswoman in Washington.

"They are only lightly armed, some have military training and others do not," Levinson said of the new Iraqi soldiers. "But they have a familiarity with Iraqi society and can be a bridge between coalition forces and the civilian population."

In the north and south, the Iraqi forces will be controlled by the U.S. war commander, Gen. Tommy Franks. They may fight, work as language translators, be liaisons with local populations and so on, Defense Department officials said Sunday.

"We are proud to contribute our forces," Ahmad Chalabi of the INC said in a statement Sunday from Nasiriyah.

"The war of national liberation which Iraqis have waged for 30 years is now nearing its end," he said. "We call on the Iraqi people to join with us in removing the final remnants of Saddam's Baathist regime."

The new groups join several dozen Iraqis who were trained by the U.S. Army in Hungary -- called "Free Iraqi Forces" and wearing FIF patches on their U.S.-supplied uniforms. That group is already working with civil affairs troops in the southern port of Umm Qasr, helping screen and hire local Iraqis for distribution of humanitarian supplies and other jobs.

Like the newly deployed Shiites, the liaisons in Umm Qasr were sent as close as possible to their former home areas or places where they'll have the most rapport with local populations, officials said.

The difference is that there was not time to train the new groups before the war started, they said.

Iraqi opposition groups last year submitted the names of thousands of men who they said would fight alongside American forces. They were from around the world and represented major Iraqi groups, including the Shiites, Sunnis and Kurds, officials said then.

Screening to weed out possible Saddam spies or people with criminal records -- as well as planning and other issues -- delayed the training. The first group was assembled in mid-January and only two groups -- a total of around 80 -- went to the monthlong boot camp before the war started March 20. The training was discontinued March 31.

Officials had said previously that they could train up to 3,000.

Appearing on ABC's This Week, Pace was asked if the participation of INC soldiers would give that group unfair advantage as Iraq's new government is formed.

"The fact that they may be from one section of the population or another at this point in time on the battlefield is not significant," he answered.

"I'm comfortable that once we free Iraq and give it to the people in Iraq, that they will be able to decide for themselves who should be their leaders," Pace said.