Updated

Two units of about two dozen Army soldiers each moved into position around two airfields in northern Afghanistan early Thursday, providing security and highlighting the continuing danger in areas recently wrested from Taliban control by opposition forces.

The two teams will help guard U.S. military personnel helping to repair airfields in Mazar-e-Sharif and north of Kabul in Bagram, military officials said Wednesday.

The soldiers are from the 10th Mountain Division, which has about 1,000 soldiers providing security at an air base the Americans are using in Uzbekistan.

The soldiers also will help protect U.S. forces setting up field hospitals, coordinate food deliveries and advise anti-Taliban fighters, military officials said, speaking on condition of anonymity. Similar security teams probably will be sent to other areas of Afghanistan, one official said.

Bagram's airfield, which had been a key base for the Soviet Union during its occupation of Afghanistan in the 1980s, eventually may be used to launch U.S. combat operations, officials said. It was not clear whether those missions would involve strike aircraft or ground troops.

Although the anti-Taliban Northern Alliance now controls the northern half of Afghanistan, the area is still dangerous. Taliban prisoners of war rioted at a fort near Mazar-e-Sharif this week, killing a CIA officer who became the first American killed in combat in Afghanistan during the anti-terrorism campaign that began Oct. 7.

Eight journalists also have been killed in Afghanistan while covering the conflict.

The 10th Mountain units are too small to deal with large-scale threats, however, officials said.

"They're not there to put down the next Taliban prison revolt," one official said.

Several hundred Army and Air Force special operations forces have been inside Afghanistan for weeks, working in small teams linked with opposition forces in northern and southern parts of the country.

The only other U.S. ground troops known to be in Afghanistan are Marines setting up a base near the southern city of Kandahar.

More Marines and equipment arrived at the base Wednesday, bringing the number to between 750 and 800, Pentagon spokeswoman Victoria Clarke said. The Pentagon has said that number may increase to about 1,100 Marines, whose purpose is to deny southern escape routes for Taliban and Al Qaeda fighters.

The Marines are the only substantial U.S. ground force in Afghanistan, although the Pentagon has not ruled out eventually putting more Army troops there if the current approach to rooting out Al Qaeda and Taliban leadership fails. For now, the Pentagon is content to seek information from local Afghans on the enemy's whereabouts and to bomb the caves, tunnels and other facilities in which they might be hiding.

Defense Secretary Donald H. Rumsfeld alluded to the possibility of more ground forces Tuesday when he visited the Tampa, Fla., headquarters of U.S. Central Command, which is managing the war effort. "Our efforts, of course, will be shifting from cities at some point to hunting down and rooting out terrorists where they hide," he said.

The Associated Press contributed to this report