The Taliban's response has been increasingly defiant, with the militia's leader, Mullah Omar, on Wednesday goading his Western foes by blaming the September 11 attacks on American "cruelty." British Prime Minister Tony Blair responded with a warning that the U.S. is poised to inflict "very considerable damage" on the Taliban regime if it maintains its refusal to hand over Bin Laden and others. With the battle lines now sharply drawn, the U.S.-led coalition is moving forces into place that would allow for various combinations of air strikes against the Taliban and terrorist camps, U.S. and British special forces deployments against specific targets on the ground, and greatly expanded military support to the Northern Alliance. Even without a large-scale invasion by forces supporting the anti-terrorism coalition, such a combination may be sufficient to put the Taliban to flight — particularly if military pressure creates cracks in the organization.

The Taliban had looked unstoppable when its troops first swept across Afghanistan in 1996 to seize Kabul. But their perceived military prowess may have been exaggerated by Pakistani logistical support, the bribing of local warlords to let them pass and the aura of power they accumulated through their rapid advance. They were badly bloodied a year later in a disastrous attempt to seize the Northern Alliance stronghold of Mazari al-Sharif. Although they have subsequently consolidated their grip over more than 90 percent of the country, the current fighting in the north suggests that grip may be somewhat tenuous. Indeed, if Western air support to an emboldened opposition deals the Taliban a series of harsh blows in succession, the movement may find many local warlords less inclined to fight to the end.

Foreign analysts have for some time suspected that there may be divisions within the Taliban over whether to risk annihilation in order to protect Bin Laden. Indeed, the movement's official position that the Saudi would be asked to leave for the good of Afghanistan suggests a measure of ambivalence. And concerted military pressure on the Taliban would likely exacerbate any current divisions.

Who would replace the Taliban?

Helping the opposition break the Taliban's grip on power would leave Bin Laden loyalists more isolated and vulnerable to attack by coalition forces. But the resulting power vacuum may create a chaotic situation inside Afghanistan. The U.S. is encouraging negotiations between different factions of the opposition with the idea of uniting them in an interim post-Taliban administration under the exiled Afghan king, Zahir Shah. But the opposition is composed of mostly ethnic-based militias who have been at each other's throats when not forced to work together against a larger enemy such as the Soviets or the Taliban. And Pakistan has warned against trying to impose a government that excludes the majority Pashto group from which the Taliban are drawn, signaling that Islamabad wants a hand in shaping a post-Taliban scenario — alongside, or in competition with such traditional neighborhood rivals as Russia and Iran.

The intensified diplomatic shuttling and the jockeying over the shape of a post-Taliban government suggests that all the region's players are positioning themselves to reap the geopolitical rewards of Western military action that all now appear to believe is imminent.