This is how the battle is playing out: Al Qaeda fighters, usually in pairs, jump out from cave entrances in the snow-covered mountain peaks and fire rocket-propelled grenades and antiaircraft missiles at US positions in the valley below.
B-52s - 10 to 15 minutes later - pummel the cave dwellers, while a US special forces team heads higher into the mountains. Their faces camouflaged, and flanked by 50 Afghan soldiers, the US troops advance in three jeeps and two all-terrain motorbikes.
As the seventh day of the largest offensive in the Afghan war began, the US significantly beefed up its presence with both US special forces troops and their Afghan allies. But at the same time, Al Qaeda and Taliban fighters strengthened their positions.
It's become clear that Operation Anaconda, which was expected to last only 72 hours, is a much tougher battle than the US expected. Both sides have suffered painful loses. Although the US has placed more than 1,000 troops on the ground to supplement their Afghan allies, they haven't been able to completely block the Al Qaeda fighters' routes in and out. The Al Qaeda and Taliban fighters - using Stinger missiles left over from the US operation here in the 1980s and led by Mullah Mohammed Omar's military commander - are hunkering down for a do-or-die showdown.
Local residents in the village of Shahi Kot say there are some 800 to 1,500 hard-line Taliban and Al Qaeda fighters - mainly Chechens - holed up here. They apparently regrouped in these fortified mountain complexes after they fled from Tora Bora, Kandahar, and Kabul earlier in the war.
Gen. Tommy Franks, commander of US forces in Afghanistan, said the number of Americans in the operation has grown by 200 to 300 over the past two days, and now totals roughly 1,100. They joined about 1,000 US-backed Afghan fighters and a small number of elite, special operations troops from six nations.
"I think the days ahead are going to continue to be dangerous days for our forces," General Franks said in Washington on Wednesday. He also raised the possibility of sending in even more firepower, including additional transport aircraft, infantry, and special operations troops. He described the situation on the ground as "very messy."
Maulavi Saifur Rehman Mansoor, the Taliban's military commander and son of a former prominent mujahideen leader and governor of Paktia Province, is leading the large group of Taliban and Al Qaeda fighters in the mountainous terrain south of Gardez.
"Maulavi Mansoor's fighters brought dozens of Stinger missiles from the Zawar Khili Al Qaeda base in early January, before it was bombed by US planes," says Haji Sardar Khan, a resident of Shahi Kot. "Al-Qaeda and Taliban fighters stockpiled a lot of food and weapons a few days before the attack began."
Operation Anaconda is taking place in the Arma Valley in the Shahi Kot mountain chain, southwest of Gardez. It is roughly a 100-square-mile patch of 800- to 12,000-foot snow-covered peaks and a series of deep, narrow, tree-covered valleys that harbor hundreds of natural rock caves and some fortified, underground bunkers.
"This area is different and more difficult than Tora Bora," says Mohammad Shakir Sahak, a tribal chief at Zarmat, which is north of Arma Al Qaeda base. "The Shahi Kot series of mountains and valleys are deeper, wider, and higher than Tora Bora."
Some 4,000 Afghan soldiers from Paktia, Logar, and Paktika Provinces have gathered at Shahi Kot to help US forces. They are flanking the US troops leading into forward positions and blocking possible escape routes.
Cmdr. Mohammad Naeem, the security chief of Zarmat District, along with 20 to 25 fighters, is blocking the route leading west from Arma.
Although he complains that he doesn't have enough ammunition, supplies, or other gear, he says: "I and my soldiers are here to block the fleeing route of Al Qaeda members who might flee from the Arma cave compound to Ghazni or to western areas," he says.
Cmdr. Raz Mohammad Totakhail, a Ghilzi warlord, along with 80 heavily armed fighters, is blocking the eastern route.
In an interview only 500 meters away from the Arma Al Qaeda base, he says: "It is very difficult to control the routes going out and coming into Arma base. The terrain is very difficult, it's very cold at this high altitude, and we don't have enough men, warm clothes, and enough communication equipment.
"On Sunday there were only a few caves and bunkers from which the Al Qaeda fighters fired grenades," Commander Totakhail went on to say. "But in the past two days, their positions have been increased to hundreds. They get fresh support from the tribal Taliban supporters on the other side of the border.
"The Al Qaeda fighters are well equipped," Totakhail says. "They are firing rockets, mortars, bombs, and heavy machineguns - fighting a guerrilla war."
"The Chechens are making hit-and-run attacks on the combined US-Afghan force of 2,000 besieging their caves and bunkers" says Commander Raz, who also fought against Soviet occupation in these very mountains during the 1980s. "They have divided into groups of four or five. They jump out of a cave, open fire on us, and then dart back into the cave or move to another one. They are familiar withthe terrain."
Residents at Rohani Baba, the closest village to the Arma Al Qaeda base, say there are dozens of families with the foreign fighters, especially the Chechens.
US and allied forces, who were brought by Chinook helicopters from Bagram airport north of Kabul, were heading toward the front line in Shahi Kot. Some troops carried shoulder-launched rockets, which they use to blast the snow-covered cave entrances. They were also equipped with night-vision equipment and dressed in heavy winter uniforms to protect them from the sub-zero temperatures.
US forces came very close to the Al Qaeda base on early Wednesday. But because the Al Qaeda fighters put up fierce resistance, the special forces weren't able to break into the northern belt of the Arma Al Qaeda base until later in the day - after a heavy US air bombardment of the caves. The exact number of casualties to Al Qaeda fighters due to the bombing is not available. But the resumption of heavy airstrikes indicates that Al Qaeda fighters continue to attack.
US warplanes also continue their round-the-clock bombardment of Al Qaeda forces holed up in cave complexes. And the US helicopters hover over the eastern edge of the mountains bordering Pakistan during and after the bombing.