Gen. David Richards, a British officer who commands NATO's 32,000 troops here, warned in an interview with The Associated Press that if life doesn't get better over the winter, most Afghans could switch sides.
"They will say, 'We do not want the Taliban but then we would rather have that austere and unpleasant life that that might involve than another five years of fighting,"' Richards said.
Afghanistan is going through its worst bout of violence since a U.S.-led invasion removed the former Taliban regime from power five years ago. The Taliban has made a comeback in the south and east of the country and is seriously threatening Western attempts to stabilize the country after almost three decades of war.
"If we collectively ... do not exploit this winter to start achieving concrete and visible improvement," then some 70 percent of Afghans could switch sides, Richards said.
Richards will command NATO's troops in Afghanistan, including 12,000 U.S. forces, until February, when U.S. Gen. Dan K. McNeil is to take command.
The British general said he'd like to have about 2,500 additional troops to form a reserve battalion to help speed up reconstruction and development efforts.
The south of the country, where NATO troops have fought their most intense battles this year, has been "broadly stabilized," Richards said.
"We have created an opportunity" following intense fighting that left over 500 militants dead in the southern provinces of Kandahar and Helmand, he said. "If we do not take advantage of this, then you can pour an additional 10,000 troops next year and we would not succeed because we would have lost by then the consent of the people."
Richards said intelligence reports indicate the Taliban is beginning to "fragment" following their defeat in the Panjwayi district of Kandahar province.
He also said that NATO troops have seen an upsurge in violence along the eastern border with Pakistan since Pakistani troops agreed to stand down in tribal areas. U.S. military officials have said the number of attacks on coalition and Afghan troops has tripled in the region.
Pakistan's government signed a deal with pro-Taliban militants on Sept. 5 to end the fighting that broke out in North Waziristan after the U.S.-led invasion of Afghanistan in October 2001. Under the deal, militants agreed to not carry out violent acts or send fighters into Afghanistan.
"There has been an upsurge in terrorist activity inside Afghanistan since this agreement was reached," Richards said.
Afghan and Western officials have repeatedly accused Pakistan of not doing all it can to block the flow of insurgents over the shared border. Pakistan rejects the charge.
But Richards, who was to travel to Pakistan for meetings with military leaders on Monday, urged "partnership and cooperation rather than confrontation" in dealings with that country.