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U.S. commander: Enemy forces 'taking a beating'

U.S. service members deployed in Operation Anaconda have faced some of the fiercest fighting since the Afghan campaign began last year.

KABUL, Afghanistan (CNN) -- Al Qaeda and Taliban fighters in the eastern Afghanistan mountains are "taking a beating" at the hands of U.S.-led coalition and Afghan forces, U.S. operation commander Maj. Gen. Frank Hagenbeck said Wednesday in Afghanistan.

But U.S. officials in Washington cautioned that they have indications that al Qaeda and Taliban fighters were regrouping across the border in Pakistan.

The sources would not say precisely what evidence they have, but one official told CNN, "We see indications al Qaeda may be trying to regroup in Pakistan with a view to then heading back into Afghanistan."

Former Pakistani Prime Minister Benazir Bhutto told CNN she, too, is concerned that the "militants are going to land up in Pakistan, try to regroup there and redirect their efforts in southern Afghanistan and perhaps other parts of the world."

VIDEO CNN's Martin Savidge traveled with U.S. forces during the first days of Operation Anaconda in eastern Afghanistan (March 6) Play video (QuickTime, Real or Windows Media) U.S., allied and Afghan forces attack al Qaeda and Taliban fighters hiding in the mountains (March 6) Play video (QuickTime, Real or Windows Media)   MORE STORIES Service members' remains arrive in U.S.    EXTRA INFORMATION Images from Operation Anaconda  Map of Afghanistan  showing the location of the fighting Operation Anaconda

In Washington, Defense Secretary Donald Rumsfeld told reporters that the ongoing operation against al Qaeda and Taliban fighters who are in cave and tunnel complexes of Paktia province south of Kabul is "not the first major battle, and certainly won't be the last."

He said the U.S. objective is to make sure that terrorists have "no sanctuary, no safe haven" from which to operate.

"You cannot defend against terrorists by hunkering down," Rumsfeld said. "You simply must go after them. That is the only proper defense is an offense."

Hagenbeck told reporters the U.S. military has indications of other "pockets of terrorists" around Afghanistan, and he said the operation against al Qaeda and Taliban fighters who are regrouping in cave and tunnel complexes of Paktia province, south of Kabul, would not be "the first and last big battle of this war."

He said the fighters are coming in from the south and east, in small groups of five and six. When asked how long he expected the fight to continue, Hagenbeck said that was up to the enemy.

"As long as they want to send them here, we'll kill them here," he said. "If they go somewhere else, we'll ... kill them wherever they go."

Rumsfeld said the American operation had killed "many hundreds" of Taliban and al Qaeda fighters, including "a number of senior leaders."

Allied forces have pounded al Qaeda and Taliban fighters hidden in the mountains of Paktia province since the mission, dubbed Operation Anaconda, began. Hagenbeck said the operation was conceived after intelligence reports indicated enemy forces were preparing a terrorist attack against Afghanistan's interim government, led by Hamid Karzai.

Gen. Tommy Franks, commander of the U.S. Central Command, said that the strength of the al Qaeda resistance to the operation was not wholly a surprise, although intelligence was not always clear about the "particulars of where (al Qaeda forces) might be."

Franks said the operation will continue "until we have completed our objective."

"The sense right now is that there has been no effort from the enemy to leave the area," he said. "Their choice is either to surrender or they will be killed."

Wounded troops arrive at Ramstein Air Base in Germany.

Eight American service members have been killed and more than 40 wounded since the operation began, and are the latest casualties since the war on terror began almost five months ago. (Full Story) The remains of seven of those killed arrived early Wednesday at Dover Air Force Base in Delaware. (Full story)

An undetermined number of Afghan forces also have died in the operation, including at least four who died over the weekend.

About 2,000 U.S., allied and Afghan forces are involved in the operation, which began with intense bombing Friday night near Gardez, the provincial capital of Paktia, about 100 miles (160 kilometers) south of Kabul.

The original mission was supposed to last 72 hours, but the operation has gone on for four days and it is evident Taliban and al Qaeda forces, with no place to run, don't plan to surrender.

"We have had them boxed in," Hagenbeck said. "Some local fundamentalists called a jihad against the Americans and their coalition forces. They have been funneling, infiltrating fighters into this area."

U.S. officials estimated Tuesday that several hundred pro-Taliban fighters were in an area near Gardez and that defeating them might take a week to 10 days.

"They are extraordinarily well dug-in and expected to fight to the death," an official said, acknowledging "it is an awful place to fight a war."

Much of the fighting is at elevations above 11,000 feet, where thin air makes breathing more difficult. The altitude is also near the flight limit for some U.S. combat helicopters, officials said.

Interim Afghan leader: No victory yet

Meanwhile, Afghanistan's top military commanders stopped short of declaring victory Wednesday as they met in Kabul for a two-day session to discuss how the country will handle the war on remaining al Qaeda and non-Afghan Taliban forces.

Interim leader Karzai was expected to declare a victory in the fighting in Paktia, a top ministry official said.

"In three months time, with the help of the coalition, we defeated the Taliban and pockets of terrorism," Karzai said, stopping short of mentioning the most recent battles.

As U.S. warplanes flew overhead during Wednesday's news conference, Karzai and Afghanistan's interim defense minister, Gen. Qassim Fahim, said Afghanistan should build its own army to defend the country.

Afghanistan's top military commanders, various Cabinet members as well as U.N. special envoy Lakhdar Brahimi and the head of the International Security Assistance Force attended the news conference.

"I want to promise to all Afghanistan that we are going to be able to eradicate the terrorism in Afghanistan," Fahim said to nods and applause.

CNN Correspondents David Ensor and Martin Savidge contributed to this report.