A U.S.-marked aircraft arrived in Uzbekistan on Saturday, a day after President Islam Karimov granted permission for U.S. warplanes and troops to use an Uzbek air base for military operations against Afghanistan.

A cameraman for Associated Press Television News observed an aircraft with U.S. markings flying overhead near the Khanabad air base, about 180 miles southwest of the capital, Tashkent. An Associated Press photographer also saw a similar, large military plane taking off from the base.

A local police officer, who refused to be named, said that three or four planes had already landed. His report could not be confirmed.

Pentagon spokesman Jim Turner refused to comment on Saturday, in keeping with the Pentagon's policy of not discussing troop movements. The Pentagon has said repeatedly since the Sept. 11 attacks that for safety and other reasons it will not discuss details of its campaign to root out Usama bin Laden and supporters. The campaign is expected to make heavy use of U.S. special forces working clandestinely.

There was only indirect evidence suggesting a new military presence. Earlier this past week, reporters could easily walk up to the Khanabad base perimeter and drive straight up to the front gate. But on Saturday, many more Uzbek police and military checkpoints had been erected on roads leading up to the base, with guards brandishing Kalashnikov automatic rifles and turning back all cars without special permission to enter.

Karimov on Friday granted permission for U.S. warplanes and troops to use an Uzbek air base to support President Bush's campaign to root out terrorists in neighboring Afghanistan.

The Army has dispatched 1,000 infantry soldiers skilled at search-and-rescue, humanitarian missions and helicopter assaults.

The deal struck by Defense Secretary Donald H. Rumsfeld and Karimov gave the Pentagon a foothold it needs inside Uzbekistan, a former Soviet republic on Afghanistan's northern border.

But it was not clear from Karimov's comments on Friday whether it provided the wide latitude U.S. officials had sought for putting a military squeeze on Afghanistan's Taliban.

"We have offered one airfield in Uzbekistan, with all the surrounding facilities, in order to deploy a limited number of (U.S.) transport airplanes and helicopters," Karimov said through an interpreter at a news conference with Rumsfeld.

"I envisage that the equipment will be used for humanitarian operations and for search and rescue operations," he said.

Karimov said no U.S. special operations forces — such as Army Rangers or Green Berets who specialize in operating behind enemy lines — would be allowed to operate from Uzbek territory.

"We are not quite ready for this," he said when asked why no special forces would be permitted.

U.S. officials said Friday that the U.S. Army was sending about 1,000 infantry soldiers to this former Soviet republic.

The large air base at Khanabad is now home to Uzbekistan's ground-attack Su-24 planes.