KABUL, Afghanistan (AP) _ A U.S. special-forces gunship swung into action Tuesday, raking a Taliban stronghold in Afghanistan with heavy machine gun and cannon fire. Fierce daylight bombing at Kabul set two International Red Cross warehouses afire.
Massive explosions from the battle over Kabul's skies could be heard along the front lines between Taliban and Afghan opposition forces 30 miles to the north. Huge clouds of black smoke billowed on the capital's northern edge.
The second straight day of fierce daylight raids and the first use of the low-flying, lumbering AC-130 marked an intensification of the air campaign against Taliban military sites and leaders.
It also signaled U.S. confidence that more than a week of attacks by ship-launched cruise missiles and high-flying jets had greatly eased the threat from Taliban air defense.
Secretary of State Colin Powell, in neighboring Pakistan to shore up support for the U.S.-led campaign, said Afghanistan's Islamic regime was ``under enormous pressure'' but refused to say whether he thought it was near collapse.
Tuesday's fresh waves of air strikes targeted the Taliban on multiple fronts - military bases and airports outside the capital of Kabul, Taliban leaders' southern base city of Kandahar and the key northern city of Mazar-e-Sharif - a former opposition stronghold.
Salvos of bombs struck in the north of Kabul throughout the day, blasting at a cluster of Taliban military bases and transport and fuel depots.
One bomb crashed into a Red Cross compound at Khair Khana, injuring a guard and setting two warehouses afire. Afghan workers braved the smoke to recover some of the blankets, tents and medicine from one building. The other contained wheat, ICRC staffers at the scene said.
In Islamabad, Pakistan, ICRC spokesman Mario Musa said the warehouse roofs had been marked with a Red Cross insignia.
U.S. officials said they were trying to determine whose firepower struck the warehouses.
``In a case like this ... It's hard to say whether something was a result of anti-aircraft weaponry that was shot from the ground, or other weapons that were shot from the ground and came back down, or whether or not it was coalition efforts,'' White House spokesman Ari Fleischer said in Washington.
Outside Kabul, an Associated Press reporter with opposition forces on the Shomali plain well to the north of the capital could hear huge explosions from the bombardment and the roar of heavy guns.
Taliban fuel supplies and vehicles were believed to have been removed from some of Tuesday's targeted installations in the Khair Khana area. Residents said Taliban forces are avoiding spending the night at the Khair Khana military bases, taking refuge in local mosques instead.
Locals say Tuesday's bombing injured three farmers out working in their fields when the U.S. jets roared overhead.
Taliban Information Ministry official Abdul Himat said 13 civilians died in the pre-dawn assault at Kandahar. The Taliban also said two people were killed in Tuesday's attack on Mazar-e-Sharif. The claims could not be independently verified.
In Washington, a defense official confirmed the overnight attack was led by an AC-130, marking the first acknowledged use of special-forces aircraft in the offensive, which began on Oct. 7. The official spoke on condition of anonymity.
Previous raids had targeted anti-aircraft artillery sites and other military installations with the aim of making the skies safe for aircraft like the AC-130. The Taliban are believed to still hold an unknown number of shoulder-fired Stinger missiles capable of bringing down aircraft, however.
High-firepower AC-130s typically are used to support ground forces trained for small-unit operations. There was no word whether the gunship's deployment meant special forces had entered the battle on the ground.
Aiming to make the skies safe, U.S. forces have made particular targets out of airports in Taliban territory throughout the campaign. Attacks put the Jalalabad airport in eastern Afghanistan out of commission almost from the start.
Other strikes have pounded Taliban jets at Kabul and the sprawling airport complex at Kandahar, which holds at least 300 housing units of Osama bin Laden's followers.
The only other major airfields in Taliban territory, at Shindand in southwestern Afghanistan and in Herat, have also taken repeated strikes.
The United States launched the air campaign to root out bin Laden - the top suspect in the Sept. 11 terror attacks on the United States - and to punish Afghanistan's rulers, the Taliban Islamic militia, who harbor him.
Defense Secretary Donald H. Rumsfeld, speaking at the Pentagon, suggested Monday that U.S. airstrikes could next start targeting Taliban front-line positions facing Afghan opposition fighters in the northeast.
``I suspect that in the period ahead that's not going to be a very safe place to be'' for Taliban fighters, Rumsfeld said.
Taking advantage of the massive assaults, opposition forces on the ground claimed Monday to have advanced within miles of Mazar-e-Sharif.
In the Tajikistan capital Dushanbe, a spokesman for the opposition northern alliance said opposition troops were approaching Mazar-e-Sharif from the northeast and northwest and that some units were as close as 4 miles away.
The claim by Abdul Vadud, the military attache of the opposition-controlled Afghan Embassy in Dushanbe, could not be confirmed.
Mazar-e-Sharif is the largest city in northern Afghanistan and is dominated by ethnic minority Uzbeks. The fundamentalist Taliban, who are Sunni Muslims, captured the city in 1998 and have since ruled it with an iron hand.
Taking the city would enable the opposition to consolidate its grip on the small area it controls in the north, since the town controls routes running east to west and linking pockets of the northern alliance's strength.
Pakistan, which has agreed to lend logistical support for the campaign, has pressed for the U.S. and British offensive to avoid directly helping opposition troops. Pakistan fears the northern alliance, its longtime opponent, will seize power from the Taliban.
With Powell beside him, Pakistani President Gen. Pervez Musharraf told an Islamabad news conference Tuesday the military strikes should ``short and targeted.''