U.S. infantry moves into northern Afghanistan

One force near Mazar-e-Sharif is made up of no more than two dozen soldiers, the officials said, speaking on condition of anonymity. The other unit at the Bagram airfield north of Kabul has about the same number, officials said.

More such rapid response teams probably will be used in other areas of Afghanistan, one official said.

The 10th Mountain has had about 1,000 of its soldiers providing security at an air base across the border in southern Uzbekistan for several weeks, the officials said.

The 10th Mountain soldiers will provide security for U.S. personnel helping to repair runways, set up humanitarian relief and advise anti-Taliban forces at both locations, one official said. The security forces are used with the permission of anti-Taliban commanders in the area, the official said.

The rapid-reaction force apparently was not in the Mazar-e-Sharif area when Taliban prisoners staged a bloody prison revolt Sunday.

The CIA confirmed Wednesday that one of its officers, Johnny ``Mike'' Spann, was killed in the riot. Spann, a native of Winfield, Ala., who lived in a Virginia suburb, was the first American known to be killed in Afghanistan since U.S. bombing began Oct. 7.

Bagram's airfield might eventually be used to launch combat operations, officials said, although it was not clear whether that would be by strike aircraft like Air Force F-15s or by ground troops.

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-Qaida 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-Qaida and Taliban leadership fails.

For now, the Pentagon is content to seek intelligence 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. ``This is difficult work. It's dangerous work.''

An Afghan woman was killed Tuesday when bundles of wheat, blankets and cold weather gear fell on a house about 120 miles northeast of Mazar-e-Sharif, the military said Wednesday. Although a U.S. Central Command statement said a child also died in the mishap, a spokesman later said that the child had been knocked unconscious, not killed.

``The U.S. deeply regrets any loss of life,'' the statement said. ``Great time and care goes into the selection of sites for the delivery of humanitarian assistance.''

Pentagon officials, meanwhile, said leaflets dropped by American planes over Afghanistan are helping persuade some Taliban troops to give up their fight.