Low-flying, slow-moving special forces gunships cruised over the skies of Afghanistan Monday, defense officials said. The step signaled the air campaign was shifting focus from military facilities to the Taliban leadership.

Video:  Air Strike on Afghanistan I   Air Strike on Afghanistan II

Late Monday, a senior defense official confirmed to Fox News that a special operations mission was underway south of Kandahar. Government sources said AC-130 gunships were being used for the mission in combination with "task force 160," the elite special forces helicopter unit. Sources said the mission was targeting Brigade 55, the Taliban's elite forces.

Pentagon officials said they expected to touch upon this mission in their briefing Tuesday morning — if they have enough battle damage assessment to show or talk about.

The AC-130 turboprop airplane is used by American ground forces trained for small-unit operations in hostile country. It was the first acknowledged use of special forces aircraft in the conflict.

"We felt it was the appropriate weapon to be used," said the defense official, speaking on condition of anonymity. He declined to discuss specific targets or results.

Raids in the first nine days of the campaign targeted air defense and other military facilities with the purpose of making the skies safe for less agile aircraft like the AC-130.

The Afghan capital of Kabul shook from huge explosions through the day and into the night on Monday, sending terrified residents scurrying for shelter, as U.S. jets pounded suspected weapons storage sites in Kabul and across the country.

The opposition alliance claimed Monday it had advanced close to Mazar-e-Sharif, the largest city in the north, and that some 4,000 Taliban troops defected over the weekend. The Taliban denied the defection claim.

Speaking at the Pentagon, Defense Secretary Donald H. Rumsfeld suggested that U.S. airstrikes may start targeting Taliban front-line positions facing Afghan opposition fighters in the northeast of the country.

The attacks Monday against Kabul started just before sunrise and continued through the day into the night. Taliban gunners fired in vain at the attacking planes, some so high they could not be heard from the ground.

The attacks in Kabul appeared to be directed at weapons and ammunition storage sites in the hills north of the city of 1 million people and around the airport.

In one nighttime raid, 10 huge explosions in the direction of the airport shook buildings miles away.

One bomb exploded near a U.N. World Food Program warehouse on the northern edge of Kabul, slightly injuring one Afghan employee, U.N. spokesman Khaled Mansour said in Pakistan.

In the Jalalabad area of eastern Afghanistan, U.S. jets struck the regional military headquarters near the airport and Tora-Bora, a suspected terrorist training camp of Usama bin Laden.

An Afghan refugee arriving in the Pakistani border town of Chaman said a suspected ammunition depot in Kandahar, the southern city where the Taliban leadership is based, was ablaze after a hit Monday by U.S. missiles.

The United States launched the air campaign on Oct. 7 to root out bin Laden — the top suspect in Sept. 11 terror attacks in the United States — and to punish Afghanistan's rulers, the Taliban hard-line Islamic militia, who harbor him.

In other developments Monday:

• In neighboring Pakistan, pro-Taliban Islamic militants closed thousands of shops throughout the country and clashed with police to demand an end to the bombing campaign. But compliance with the strike was limited, and some shops were open even in border cities where sympathy with Taliban is high.

•   U.S. Secretary of State Colin Powell arrived in Pakistan to meet with President Pervez Musharraf and discuss reopening military ties.

•   The USS Theodore Roosevelt was getting into position in the region, bringing to four the number of aircraft carriers involved in the campaign.

•   The U.S. military has paid millions to buy exclusive rights to some of the commercial sector's best satellite imagery of Afghanistan — aiming to prevent the Taliban from getting hold of it.

The Taliban Information Ministry claimed 12 people died Monday during a raid in western Badgus province. The Taliban said some 200 civilians were killed Thursday when U.S. jets attacked the village of Karam in eastern Afghanistan.

In Washington, Rumsfeld said some of the Taliban casualty claims were "ridiculous." But he acknowledged that some Afghan civilians have been killed unintentionally, without offering specific numbers.

He said U.S. planes have so far avoided striking Taliban positions on the front lines because of incomplete targeting information. But he said that might soon change.

"I suspect that in the period ahead that's not going to be a very safe place to be" for Taliban fighters, he said. "We hope to have improved targeting information in the period ahead."

Pakistan, a key U.S. ally, has pressed for the U.S.-led air campaign not to directly help opposition troops. Pakistan fears the Northern Alliance, its longtime opponent, will seize power from the Taliban.

The Afghan opposition said Monday its troops had advanced to within three miles of the airport at Mazar-e-Sharif, a strategic city the Taliban have held since 1998.

"Thank God, the Taliban forces are unable to take the help of their air forces," opposition spokesman Mohammed Ashraf Nadeem said.

The claim could not be independently verified, and the Taliban had no immediate comment.

But Taliban officials denied an opposition claim that 4,000 of the militia's fighters under a single commander had surrendered to rebel troops on Sunday. Taliban Information Minister Qudratullah Jamal said the commander in question had never had so many soldiers under his authority.

There were signs the attacks were increasing the suffering of the Afghan people, already impoverished after more than 20 years of civil conflict.

At a Kabul hospital, doctors and mothers said the nightly power cuts were threatening the lives of newborns, especially premature babies who require incubators.

"Please have mercy on us and don't kill us," begged Rahim Biba, mother of an infant born two months prematurely. "We are already in trouble. Don't add to our miseries."

Leaflets Added to Military Operation

The Pentagon has begun a new leaflet campaign aimed convincing the Afghan people the strikes are meant to help them.

"We're working to make clear to the Afghan people that we support them and we want to help free their nation from the grip of the Taliban and their foreign terrorist allies," Rumsfeld told reporters.  For the first time Sunday leaflets — in the local languages of Pashtu and Dari — were added to the drops already being made of humanitarian food packets for the Afghan population, said Gen. Richard Myers, chairman of the Joint Chiefs of Staff, who appeared with Rumsfeld.

One leaflet shows a Western soldier in camouflage and helmet shaking hands with a man in traditional Afghan dress in front of a mountain scene.

"The partnership of nations is here to assist the people of Afghanistan," the leaflet said.

Another depicts a radio transmitting tower and sketches of radios and tells times and radio stations to tune to for what it calls "Information Radio." The broadcasts started earlier, but leaflets telling people to listen were delayed because of windy conditions last week, a Pentagon official said.

Over the weekend, more than 68,000-plus ration packets were dropped, bringing the total to 275,000 since the effort began.

"This is bringing needed food to hungry Afghan people, as well as a message of friendship from the American people," Rumsfeld said.

"Many, if not most Afghans, I believe, want little or nothing to do with the Taliban, who have turned their nation into a base from which foreign terrorists wage war on the rest of the world, while they starve or are displaced," he said.

The Associated Press contributed to this report.