Al-Qaida's role in Afghanistan has faded after eight years of war. Gone is the once-formidable network of camps and safe houses where Osama bin Laden and his mostly Arab operatives trained thousands of young Muslims to wage a global jihad. The group is left with fewer than 100 core fighters, according to the Obama administration, likely operating small-scale bomb-making and tactics classes conducted by trainers who travel to and from Pakistan.
President Barack Obama said Tuesday that al-Qaida has "lost operational capacity" after a series of military setbacks and vowed to continue the battle to cripple the terror organization.
With the U.S. reassessing how to achieve that objective, the key question now is whether al-Qaida could reconstitute its Afghan base even if its Taliban allies regain power.
NATO casualties have risen dramatically this year at the hands of a resurgent Taliban, and U.S. Gen. Stanley McChrystal is asking for up to 40,000 more American troops so that he can bolster security, especially in northern and western Afghanistan.
Opponents of that strategy, notably Vice President Joe Biden, prefer to maintain current U.S. troop levels _ about 65,000 _ and shift the focus to missile strikes and special forces operations in neighboring Pakistan, where many key al-Qaida figures have sought sanctuary.
Those critics believe the Taliban _ a radical Islamist movement that emerged among the ethnic Pashtun community and ruled in Kabul from 1996 until 2001 _ pose no threat to the United States. They say the real enemy, al-Qaida, lies across the border in Pakistan.
U.S. national security adviser James Jones said last weekend that the al-Qaida presence has diminished and he did not "foresee the return of the Taliban" to power.
He said that according to the maximum estimate, al-Qaida has fewer than 100 fighters operating in Afghanistan without any bases or ability to launch attacks on the West.
"If the Taliban did return to power, I believe we are strong enough to deter them from attacking us again by strong and credible punishment and by containing them with regional allies like India, China and Russia," said former State Department official Leslie Gelb.
But Bryan Glyn Williams, a University of Massachusetts associate professor who monitors militant Web sites, told The Associated Press he has collected reports of large numbers of al-Qaida fighters in various provinces in addition to across the border in Pakistan.
Michael Scheuer, a former CIA analyst who tracked bin Laden for three years, believes the administration may have underestimated al-Qaida's role here because the organization prefers to work in the background providing logistics, propaganda and training to local allies.
Most of the foreigners fighting against NATO in Afghanistan are believed to be Pakistani Pashtuns and Uzbeks, who are harder to identify than Arabs because of ethnic similarities to Afghans.
Although the Taliban never fully embraced al-Qaida's doctrine of global jihad, the movement has spread among ethnic Pashtuns in Pakistan, threatening the stability of that nuclear-armed country.
"When you see less and less of al-Qaida in an Islamist insurgency, it almost certainly means that it is more effective than when you saw more of it," Scheuer said. "I am sure that al-Qaida is still fielding some field-grade cadre to toughen the Taliban's ranks."
Some experts believe al-Qaida operates in Afghanistan through Lashkar al-Zil, or "Shadow Army," which is believed to have carried out attacks in eastern Afghanistan and Pakistan.
"In my opinion al-Qaida fighters from the Lashkar al-Zil are actively involved in all Taliban fronts, from Nuristan in the north to Helmand in the south," Williams said. "While foreigners do not play a considerable role in the current jihad, al-Qaida is definitely there."
Even those who doubt bin Laden's followers could stage a cmeback won't rule out that possibility, given Afghanistan's tribal-based politics where alliances forged today are discarded tomorrow.
"Afghanistan is a complicated place that has always worked on the basis of discussions and deals where nobody comes out a complete loser and nobody comes out a complete winner," said Richard Bassett, the U.N.'s chief al-Qaida and Taliban watcher.
Nevertheless, al-Qaida's presence has vastly diminished since the Sept. 11, 2001 terror attacks that triggered a U.S.-led invasion a month later.
U.S. officials in Afghanistan rarely mention al-Qaida in sharp contrast to Iraq, where the U.S. military was quick to blame the group for most attacks against Shiite civilians.
If there are significant numbers of Arab al-Qaida members left in Afghanistan, they maintain a low profile. During the years of Taliban rule, many Afghans deeply resented the presence of swaggering young Arabs, who in turn looked upon their hosts as backward and primitive.
Bassett, the U.N. Taliban watcher, believes Taliban leader Mullah Omar would never allow al-Qaida operatives free rein again because he blames them for provoking the war that drove his Islamist group from power.
"Al-Qaida has sort of sensed their future lies more with the Taliban groups in Pakistan than with the Taliban groups in Afghanistan," Bassett said.
However, al-Qaida has maintained longtime ties with a number of key figures within the broad coalition that is fighting U.S. and NATO forces in Afghanistan.
Chief among them are Jalaluddin Haqqani and his son Sirajuddin, whose Pakistan-based forces are battling the Americans and their allies across eastern Afghanistan. NATO officials say the Haqqani group, among the most feared fighters in Afghanistan, may have taken part in the Saturday assault on a U.S. outpost in Nuristan province that left eight American soldiers dead.
Another faction with longtime al-Qaida ties is led by Gulbuddin Hekmatyar, a former prime minister and rebel commander in the war against the Soviets in the 1980s.
"Al-Qaida is still very close with Hekmatyar and is also tight with the Haqqanis," said Bruce Hoffman, a counterterrorism expert at Georgetown University. "I think one of the problems is that the Americans see the Taliban as a monolithic entity."
Hoffman believes a U.S. failure in Afghanistan would be spun by al-Qaida as a victory that would invigorate the group regardless of whether it returned to Afghanistan in force.
"They faced annihilation seven years ago and they have certainly rebounded from that setback," Hoffman said. "Withdrawal would be an enormous tonic to them in two respects: the propaganda value would be a game changer. They would portray it as having defeated the only other superpower in the world."
Michael O'Hanlon, a research director of the Brookings Institute, agrees a Taliban victory "would be a big deal for us" because of the psychological boost it would give to al-Qaida and associated movements it inspires around the world.
"It would allow al-Qaida to say they got the momentum back, after a couple of years in which America did better against them in other locations," he said.
Robert H. Reid is AP chief of bureau for The Associated Press in Kabul and news director for Afghanistan and Pakistan. AP writer Kathy Gannon in Islamabad and researcher Jennifer Farrar in New York contributed to this report.