A unit of the 173rd Airborne, based in Vicenza, Italy, went into the north Wednesday night, said Lt. Col. Thomas Collins, spokesman for the U.S. Army Southern European Task Force. 

The soldiers from the Army's 173rd Airborne Brigade dropped into an airfield and set up security for the site, which will be used to bring in supplies and support personnel, a senior Pentagon official said. 

Giving cover for the deployment, U.S. warplanes struck Iraqi ground troops and bunkers in northern Iraq. Three waves of combat planes from the USS Theodore Roosevelt hit "ground troops, command and control bunkers, artillery positions and ... a surface to air missile battery," said Lt. John Oliverira, the ship's public affair officer.

The airdrop was a dramatic entry for ground troops into a region where until now only small groups of U.S. Special Forces were operating, working with U.S.-allied Kurdish fighters in preparation for a northern front against Saddam's forces. Coalition airstrikes have been hitting Iraqi military forces and other strategic targets.

Early Thursday, Kurdish fighters closed off a highway and roads near the airstrip where troops were said to be arriving, outside the town of Bashur, about 30 miles northeast of the Kurd-controlled city of Irbil and 30 miles south of the Turkish border.

From the highway, dusted from a recent snow, a flashing light from the airstrip's control tower was visible in the distance, and three helicopters could be seen landing, flying with nearly all their lights extinguished.

The paratroopers, including elite Army Rangers, jumped out of low-flying C-17 Globemaster transport planes into Bashur airstrip, according to a Philadelphia Inquirer reporter accompanying the unit. There was no hostile fire during the drop, the Pentagon officer said.

Once on the ground, the reporter said, they scrambled to set up a security perimeter and traffic checkpoints around the airfield. Future airlifts into the area will include supplies and support personnel for the 173rd's fighters, defense officials said. The airfield's 6,700-foot runway is long enough to land C-17s and other U.S. military cargo planes.

"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.

Collins refused to say whether the 173rd deployed directly from Italy into Iraq or had taken a different route. Italy's parliament voted this month to allow U.S.-led coalition forces to use Italian air space and military bases -- but not for directs attacks on Iraq.

It was not clear if the deployment would violate the terms of the country's involvment, but the matter immediately sparked controversy in Italy, where there is a strong anti-war movement.

Pentagon officials have said for weeks they would have U.S. forces in northern Iraq to open another front against Saddam's forces. The vast majority of the coalition ground troops in Iraq are moving toward Baghdad from the south after entering from Kuwait.

Pentagon officials 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 say 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.

Though no hostilities were expected during the deployment, the 173rd decided to parachute in rather then ferry troops in by plane so that a significant combat force could mass almost immediately to protect itself, officers said, according to the Inquirer reporter.

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.

Another key mission for the 173rd could be to keep order in northern Iraq, which is controlled by two semi-autonomous Kurdish factions but also includes several splinter groups and a base for the Al Qaeda-linked Ansar al-Islam. Turkey has said it may send more troops into northern Iraq to prevent refugees from moving north, while U.S. officials have said they advised Turkey against sending large additional forces into northern Iraq