For months, US-led forces in Afghanistan have fought what many experts dubbed a new "Afghan model" kind of war, combining air power, proxy forces, and US special operations units.
Now, suddenly, the US and its allies are in the fray of an old-fashioned ground war, as they try to root out Al Qaeda and Taliban remnants dug into caves in snow-covered mountains south of Gardez.
The commitment of sizable numbers of US and Western troops suggests that commanders have learned a lesson from the December siege of Tora Bora, when Afghan proxy forces may have let hundreds of enemy fighters escape.
But as mounting casualties show, greater risk is an inherent part of this new head-on confrontation. US fighters are directly taking on the harsh elements that have long thwarted foreign armies in Afghanistan: frigid, high-altitude passes, hundreds of fortified caves and tunnels, and an entrenched enemy. "These guys aren't running," says one Pentagon official. "They wanted to fight us one-on-one on the ground in a Soviet-style scenario - and they are getting what they wanted."
The fight could end up being the biggest and most deadly in the Afghanistan war.
At least nine US servicemen have been killed in the battle. Six troops died when one of the MH-47 Chinook helicopters crashed and troops aboard engaged in close ground combat with enemy forces. Another fatality occurred earlier, when a MH-47 was hit, but managed to land safely. Dozens of other US troops have been wounded since the campaign began Friday.
The battle between some 1,500 coalition troops and an estimated 500 to 1,000 Al Qaeda and Taliban fighters is likely to be drawn out. "It's not going to be over today," one official says.
The use of more US and Western ground troops signals a shift in military strategy from earlier stages of the conflict. After the December siege at Tora Bora led to the escape of hundreds of Al Qaeda and Taliban fighters, possibly including Saudi militant Osama bin Laden, US commanders became less confident of relying greatly on Afghan proxy forces on the ground.
"We may be correcting some things by sealing the borders and relying more on our own guys," says Mackubin Owens, a Marine veteran and strategist at the Naval War College in Newport, R.I.
"You still need troops on the ground other than Special Operations Forces" combined with air power, he says. "It's like the Zen question: Which blade of the scissors does the cutting? They both do.... You need ground forces to get the enemy to mass so you can destroy them with air power."
The deployment of a large American ground contingent is also a vivid demonstration of the US determination to eliminate Al Qaeda and Taliban holdouts from Afghanistan, in an effort to help stabilize the war-torn nation under the fledgling interim administration of Afghan leader Hamid Karzai. Defense officials also say the Al Qaeda were trying to regain the opportunity to use Afghanistan as a base for terrorist operations.
Far from over
For months since the fall of the Taliban regime from power, top Pentagon officials have warned that the war in Afghanistan is far from over and that destroying Al Qaeda and Taliban "pockets of resistance" remains a prime mission.
"They are determined. They are dangerous. They will not give up without a fight," Defense Secretary Donald Rumsfeld said at a briefing yesterday.
For the first time, a sizeable number of non-US Western troops - including forces from Australia, Canada, Denmark, France, Germany, and Norway - participated together in the campaign. US officials indicated that some of the troops were likely involved because of their winter-fighting skills. Many are from NATO countries that frequently train with the United States.
Nevertheless, the current battle in eastern Afghanistan's Paktia province illustrates how risky such a mission can be.
Defense officials say that US intelligence had been tracking the regrouping of up to 1,000 enemy fighters for months, and carefully planned an assault that involved surrounding the region in an effort to cut off escape routes.
Still, the officials say, US commanders were apparently taken by surprise after Friday's campaign began by the intense resistance US forces faced from the well-armed Al Qaeda and Taliban holdouts. Mr. Rumsfeld said, however, "we ... anticipated a fierce fight."
"There was probably an assumption: We will hit them, they'll run. Let's see where they run," says one official. "If they are not running, you have a little different strategy."
The US-led coalition ground forces pulled back for a time to reposition and evacuate the wounded, while continuing to strike at enemy targets from the air. There is a likelihood that additional US ground troops, from the Army or possibly the Marines on reserve in the region, will be called in.
Although it may take time, Pentagon officials and military experts express confidence that the US-led operation will be successful, especially given the powerful arsenal of bombs at its disposal.
"If [the enemy] are in fixed positions, I don't care how well dug in they are, they are now vulnerable to 2,000-pound bombs, Daisy Cutters, and thermobaric bombs," says Mr. Owens.
This weekend US forces used at least two thermobaric bombs, which are fuel-air explosives designed to penetrate tunnels and explode inside, creating a huge wave of heat and pressure.
"We have to expect that there will be other sizeable battles of this type," Rumsfeld said yesterday.