GARDEZ, Afghanistan - More American troops and helicopters were called in yesterday to join what is already the biggest battle of the five-month Afghan war to counter attempts by the Taliban and al-Qaida to bolster the Islamic fighters who are struggling to hang on in a shrinking pocket of mountaintop redoubts.
American commanders said they had committed an additional 300 American troops to the battle in the Shah-e-Kot mountains 20 miles south of here, for a total of about 1,200 American combat soldiers. They have also ordered 16 more AH-64 Apache and five AH-1 Super Cobra attack helicopters to the fighting from bases in the United States and aboard carriers in the Arabian Sea.
American and Afghan commanders said the Taliban and al-Qaida force, numbering about 150 to 200 men when the fighting began on Saturday, had been swollen by the arrival of up to 500 new fighters who may have reached the battlefield over mountain trails.
From the mounting scale of the American military commitment, and from statements by Afghan leaders, there is a growing sense that the battle now raging could be the climactic moment of the conflict and decide whether the Taliban and al-Qaida meet their end as a fighting force in Afghanistan.
Though American officials sought to play down expectations, senior Afghan officials have even begun to hint that the real prize in the combat now unfolding at heights of up to 10,000 feet could include the capture or killing of some of the highest-ranking leaders of the Taliban and al-Qaida, perhaps even Osama bin Laden.
American commanders reported yesterday that U.S.-led bombing attacks and ground assaults may have already killed as many as 400 hostile fighters out of a total of perhaps 800, a formidable concentration for an enemy force that was in headlong flight only three months ago, and which may never have had a core of more than 5,000 men.
In an interview yesterday, the governor of Paktia province, which includes the Shah-e-Kot Valley where the battle is raging, said he had been told by American commanders that there was at least a possibility that the Taliban and al-Qaida fighters holed up in bunkers and caves might include bin Laden, the al-Qaida leader, or perhaps his deputy, Ayman al-Zawahiri.
This, said the official, Taj Muhammad Wardak, could explain why the Islamic militants have turned the battle into what is shaping up as a last-ditch struggle, displaying levels of skill and determination against the much-larger and better-equipped allied forces that the Americans acknowledge has surprised them.
"I'd say there is a 15 [percent] to 20 percent chance that Osama bin Laden is there, or if not him, then Ayman al-Zawahiri," said Wardak, an American citizen who returned from more than a decade in Los Angeles to take the governor's post last month. Asked if this was an opinion shared by American commanders who have set up a forward staging post at a mud-walled fort about two miles from the governor's headquarters in Gardez, Wardak replied, "If they didn't think so, I wouldn't be saying it."
Senior American officials, including Defense Secretary Donald H. Rumsfeld, have discouraged speculation that bin Laden could finally have been tracked down, saying that the American forces have no information to indicate that the leader or any of his top associates are in the Shah-e-Kot caves.
But Wardak, the Paktia governor, said senior American commanders had told him in recent days, based on circumstantial evidence, that they did not exclude the possibility that the main leaders might be in Shah-e-Kot, and that this might explain the do-or-die resistance encountered by American and allied troops.
These defenses, including heavy mortar, rocket and machine-gun fire from well-dug-in positions, killed eight American servicemen in the first 72 hours of the battle.
Speculation that American commanders may have deliberately downplayed the significance of the battle was heightened yesterday when Hamid Karzai, the pro-American leader of the interim government that took power in Kabul in December, told reporters in the capital that Shah-e-Kot was "the last, isolated base of terrorists in Afghanistan," and that he had told American commanders to take as much time as they needed.
At the battlefront, American tactics appeared to follow the pattern set on Tuesday, when a period of intensive bombing in the wake of early firefights in the Shah-e-Kot Valley gave way to less sustained bombing attacks and helicopter-borne ground assaults.
At an American helicopter base at Pul-e-Kandahar, on the desert floor about 20 miles west of Kabul, reporters watched as up to 15 Chinook transport helicopters, as well as Apache and Cobra attack craft, took off on sorties of about 50 miles south to Shah-e-Kot. After periods lasting an hour, sometimes two, the helicopters returned to refuel and head out again with fresh troops and supplies.
Clusters of American troops in light-brown camouflage fatigues were visible gathering by the helicopters before take-off with rifles and other weapons.
American commanders continued to stress the dangers facing the American-led troops and to say that the battle could continue for several days, a week or even longer. At his base at Bagram airfield 30 miles north of Kabul, the American officer commanding the ground offensive, Maj. Gen. Frank L. Hagenbeck of the 101st Airborne Division, whose troops are fighting alongside the Army's 10th Mountain Division and units of the Special Forces, confirmed that hundreds of additional Taliban and al-Qaida fighters had reached the Shah-e-Kot area.
"We have intelligence from a variety of sources that the local fundamentalists have called a jihad against the Americans and their coalition partners," Hagenbeck said, using the Arabic term for holy war.