Thousands of Iraqi troops marched straight out of Baghdad Wednesday on a potential collision course with coalition forces less than 50 miles away.

The Republican Guard -- Saddam Hussein's fiercest and most loyal fighters -- and a convoy of at least 1,000 enemy vehicles on the offensive streamed toward allied troops. Reports out of the Iraqi capital suggested the soldiers hoped to take advantage of tired coalition soldiers.

• Map: The War in Iraq

Meanwhile, 1,000 U.S. Army paratroopers from the 173rd Brigade dropped into Kurdish-held territory in northern Iraq, opening Operation Iraqi Freedom's northern front. The troopers planned to operate on foot, without use of vehicles.

"I can only tell you yes, they've gone in. They're on the ground," said Lt. Col. Thomas Collins, a spokesman for the U.S. Army's Southern European Task Force. The 173rd, based in Vicenza, Italy, is part of the task force.

Senior military officials told Fox News they didn't consider the movements of the Republican Guard a bad sign because they wanted to draw the well-trained Iraqi forces into open terrain so they could fight them with fortified ground troops and air power.

"Look, people seem surprised when we get into a fight on the ground," a senior military planner said. "We want a fight. We're looking for a fight."

Another senior military official said the real fight to liberate Baghdad couldn't begin until large numbers of Republican Guard divisions had been engaged in battle.

Warplanes flew over Baghdad late Wednesday night, and allied forces fired several missiles into the southern outskirts of the city.

Eight new explosions were heard by a Reuters news service witness in the skies over the outskirts of Baghdad.

In northern Iraq, the soldiers from the Army's 173rd Airborne Brigade landed at about 4 p.m. EST Wednesday, a senior Pentagon official said. He said the troops did not encounter any hostile fire.

Support forces were to be sent to the area shortly.

Future airlifts into the area will include tanks and other vehicles, supplies and support personnel for the 173rd's fighters, Defense officials said.

Several hundred U.S. special forces already were in northern Iraq, one official said, declining to elaborate on the mission. Coalition airstrikes in portions of northern Iraq controlled by Saddam's regime hit Iraqi military forces in the field and other strategic targets, the official said.

The Pentagon had hoped to have the Army's 4th Infantry Division invade Iraq from the north, but Turkey balked at allowing up to 62,000 U.S. troops on its soil to prepare for that option. The use of the 173rd shows the military has shifted to a smaller, lighter force.

Military officials said they would have liked to have secured key oil fields around the northern cities of Mosul and Kirkuk -- and perhaps the cities themselves -- by now, but they are confident of the revised plan's success.

Besides the strategic cities of Mosul and Kirkuk, another key target in northern Iraq is Tikrit, Saddam's hometown and the tribal center for most of his inner circle. Most of the Adnan Division of Iraq's Republican Guard relocated from the Mosul area to the Tikrit area shortly before the war began.

In a sandstorm that grounded other aircraft, a few helicopters managed Wednesday to evacuate wounded Marines and Iraqi prisoners and civilians, including a toddler, to a little desert airstrip.

Some had lost limbs, some had been shot, all picked up on the road to Baghdad during fire fights with Saddam Hussein's military.

The pilots were angry: As they were loading the casualties, Iraqis kept shooting. The only reason they went ahead with the mission, they said, was because children were involved.

British troops attacked a paramilitary column that had pulled out of Basra -- Iraq's second largest city -- and headed south. The column contained about 120 armored personnel carriers and tanks.

British forces said the move brought the Iraqi fighters out into the open, giving coalition aircraft a clear shot at them.

Citing military intelligence reports, Cobra pilots resupplying Marines in central Iraq said columns of 3,000 Iraqi troops were moving from Baghdad to the city of Kut along Highway 7; 2,000 more were seen south of Kut.

"I don't have a number, but we have seen reports of Republican Guards coming south in significant numbers, in strong and significant numbers," said Navy Capt. Frank Thorp, a U.S. Central Command spokesman.

Late in the day, Central Command said it believed there were about 1,000 Republican Guard members among the columns of Iraqi soldiers.

Captain Larry Burt, an officer on the staff group that has been planning for the air war for months, told Reuters Wednesday that ground troops had been moving toward Baghdad faster than expected, and Navy warplanes were adapting their missions to keep up with them.

"The army is moving at lightning speed. We had never expected them to be up there so fast," he said.

Burt added the battle was so far north that the Navy had been using F/A-18E Super Hornet strike fighter jets as tankers to refuel other planes.

Fierce Battle Outside Najaf

To the south, in Abu Sukhayr, 13 miles southeast of Najaf, coalition troops fought a fierce battle with Iraqi forces for control of a bridge over the Euphrates River, a U.S. military officer told Reuters.

An unspecified number of U.S. tanks and Bradley fighting vehicles were reportedly destroyed.

There were initial reports that the GIs, under the command of the 3rd Infantry Division, had escaped from their vehicles.

To the west, the U.S. Army's 3rd Infantry Division drew to within 50 miles of Baghdad. Other American forces were expected to join soon.

The 3rd Brigade of the 101st Airborne Division was within striking distance of Baghdad but was stalled by sand and wind storms.

"We are one tank of fuel from Baghdad," said the brigade commander, Col. Michael Linnington. "The 101st is grounded and were not doing what we do best, which is air assault operations and attacks. So we're waiting for a weather break."

Bush Rallies Troops

President Bush, rallying the troops at Central Command headquarters in Tampa, Fla., warned of a tough fight ahead as allied ground forces approach Baghdad, saying they'll face the "most desperate elements" of a "doomed regime."

"We will prevail," the president vowed. "I can assure you there will be a day of reckoning for Iraq, and that day is drawing near."

The U.S. planned to send more than 30,000 troops from the high-tech 4th Infantry Division and other units to join the Gulf fighting in a few days. The fighting force is considered one of the most modern in the military.

British Defense Secretary Geoff Hoon said Wednesday that Saddam had effectively lost control of southern Iraq and that the current focus was on providing close air support of ground troops nearing Baghdad.

At the Central Command briefing in Qatar, Brooks said commanders were "comfortable" with the way the war is going. He accused the Iraqi government of using its own civilians as human shields.

On The Road To Baghdad

Word of the Iraqi advance came as U.S. units in central Iraq appeared to be shifting their strategy because of the attacks from Iraqi militia.

Coalition forces might slow down to clear out pockets of resistance, including opposition from the Fedayeen Saddam, a militia that has been rallying other Iraqi forces to fight and preventing them from surrendering.

"We're going to start hunting down instead of letting them take the cheap shots," said Lt. Col. B.T. McCoy of the 3rd Battalion, 4th Marines.

The Fedayeen - which could number 30,000 to 60,000 -- have been accused of posing as civilians and faking surrenders in order to ambush invading forces. Other militia groups, including Saddam's Baath Party, were also operating, although some have been captured.

U.S. forces pounded targets in Baghdad with a barrage of at least 40 Tomahawk cruise missiles.

Weather temporarily halted flight operations from at least one of three U.S. aircraft carriers in the Persian Gulf.

Central Command spokesman Group Capt. Al Lockwood confirmed reports that roads and bridges to Baghdad had been wired with explosives.

"We're not surprised Saddam wired bridges to destroy them and the infrastructure of his own city," Lockwood told Fox News. "This is how Saddam operates."

Neighborhood Bombing

Iraq said two cruise missiles struck a residential area of Al-Shaab in Baghdad early Wednesday, killing 14 people and injuring 30 others. The numbers couldn’t immediately be confirmed but if accurate it would be the worst reported instance of civilian deaths in the week-long war.

Central Command said coalition aircraft used precision-guided weapons to target nine Iraqi surface-to-surface missiles and launchers in Baghdad at 11 a.m. (3 a.m. EST).

An assessment was under way to determine if the pictures being shown in Iraq of bombed civilian areas were the same areas hit in that attack.

The Pentagon vehemently denied targeting civilians, but said something did appear to have hit the area. Officials said it was not clear whether it was a stray allied missile or an attack by the Iraqis themselves.

Pentagon spokeswoman Victoria Clarke said the fact that Iraq had placed missile launchers only 300 feet from residents' homes is "a sign of the brutality of this regime and how little they care about civilians."

In Nasiriyah, Marines who secured a hospital used as a military staging area for Iraqi forces found more than 3,000 chemical suits with masks, ammunitions and military uniforms.

The Air Force used an experimental bomb Wednesday morning to knock out Iraq's state-run television, which returned to the air a few hours later. Officials declined to describe the weapon, though in recent months they said they were developing a so-called "e-bomb," which would emit an electromagnetic pulse to disrupt electronic equipment.

Senior Defense officials told Fox News that Iraqi communications sites in downtown Baghdad were high on coalition targeting lists in some of the most recent raids. The officials wouldn’t confirm that Iraqi TV was the principal target of the raids.

Meanwhile, the first shipment of humanitarian aid arrived in the southern port town of Umm Qasr. Droves of local residents clamored for the packages of food and other supplies that were tossed from the backs of military trucks.

American war losses totaled 22 dead and 14 captured or missing. Twenty British troops have died.

Coalition forces have taken nearly 4,000 Iraqi prisoners, according to U.S. officials.

Fox News' Bret Baier, David Lee Miller, Mike Tobin, Major Garrett and The Associated Press contributed to this report.