Updated

Defense Secretary Donald H. Rumsfeld told U.S. troops Sunday they are "bringing the consequences to the terrorists," but that there was no way of knowing how long it will take to finish the job and find Usama bin Laden.

In the first visit by a top U.S. official into an Afghanistan only recently freed from Taliban rule, Rumsfeld also met with the country's new interim prime minister, Hamid Karzai.

"We want to be as helpful as we can," in making Afghanistan a stable country inhospitable to terrorists, Rumsfeld said he told Karzai.

Karzai, he said, "is anxious to be cooperative with us in every possible way." Nevertheless, "it's not going to be an easy task."

They met not far from former Taliban front lines and under extraordinary security at this airfield outside Kabul, still cluttered with the wreckage of decades of wars including land mines and damaged Soviet MIGs. They sat on folding chairs in a room draped with camouflage, inside a damaged and empty aircraft hangar.

Karzai told Rumsfeld the U.S. military had boosted an Afghan opposition "incapacitated" by years of war. "The way you provided help for us was the opportunity that we wanted," Karzai said.

After the meeting and briefings from U.S. commanders, Rumsfeld stood in the gigantic hangar, the roof damaged by old mortar fire, to shake hands with some of the troops.

After the Sept. 11 attacks, Rumsfeld told the soldiers, President Bush was determined "that we let the world know that our country cannot be attacked without consequences — and you are bringing the consequences to the terrorists."

Earlier, talking to soldiers from the 10th Mountain Division at a base near Afghanistan, Rumsfeld said the fires at the World Trade Center "are still burning as we sit here, they're still bringing bodies out. Fortunately, the caves and tunnels at Tora Bora are also burning."

Yet, he cautioned: "There's no way to know how long it's going to take to find" Taliban leader Mullah Mohammed Omar and bin Laden.

Even as Rumsfeld flew around the region, the fighting near Tora Bora was evolving into a chase. Before dusk fell Sunday, the battle that had been fierce the day before, with heavy U.S. bombing, began to slow, Rumsfeld said.

About 2,000 Al Qaeda fighters were trying to flee, with opposition troops aided by U.S. special operations forces in pursuit. More than 200 Al Qaeda were believed killed in recent fighting, and 11 captured including possibly one senior Al Qaeda official, whom Rumsfeld would not identify. Rumsfeld said he got the information from Afghan leaders.

"There are people trying to escape and people trying to run them down," he said.

Rumsfeld also met with the Afghan's interim defense minister, Fahim Khan.

An international security force of between 3,000 to 5,000 troops from various countries will enter Kabul after Saturday, when Karzai takes office, Rumsfeld said. The United States will provide support, including intelligence, airlift support and a rapid reaction force in case of trouble. There are "rumblings" that a similar security force for one or two other Afghan cities is under consideration, he said.

Under ground rules set by the Pentagon, reporters traveling with Rumsfeld could not report his plans to visit Afghanistan until after his arrival.

An honor guard of rebel soldiers, in various uniforms, lined a runway only recently cleared of land mines. Rumsfeld was driven by U.S. soldiers the short distance to the hangar for the meeting with Karzai.

The hangar had been filled with the junk of past wars, including heavily damaged MIGs, when the 96th Civil Affairs Battalion based at Fort Bragg, N.C.

Throughout his visit to the region, soldiers asked Rumsfeld what might come next in the larger war on terrorism. He told one soldier flatly that he did not want to talk about Iraq. But he said destroying terrorist networks worldwide would be a long job.

Of bin Laden, he told them, "Believe me, we're looking."