The Taliban has bolstered their garrison in Kabul, as Pakistan expressed new pessimism over prospects for resolving the stand-off over Osama bin Laden.
The United States has demanded the Taliban hand over bin Laden but it refuses to.
Taliban officials have expressed defiance in the face of a potential American military strike.
They say more than 6,500 fresh troops have arrived in Kabul in recent days to beef up defences there.
Pakistan's president, General Pervez Musharraf, said that a US military strike appears likely. Pakistan has been trying unsuccessfully to mediate.
"We were interacting with them (the Taliban) so that moderation could take place and maybe this kind of action is averted," Musharraf said.
"But it appears because of the stand that the Taliban have taken, that confrontation will take place."
The president says it now "appears that the United States will take action in Afghanistan, and we have conveyed this to the Taliban."
Asked if the Taliban's days were numbered, he replied: "It appears so."
Pakistan says it will keep trying, even though it saw almost no chance of getting the Taliban to relent.
"Whatever dim hopes are left, possibilities exist," said Foreign Ministry spokesman Riaz Mohammed Khan. "We will remain engaged with the Taliban."