Even before the amount of Taliban-controlled territory in Afghanistan had shrunk to virtually nothing and Osama bin Laden's forces had beat a hasty retreat deep into the mountains, the question arose: Where should we carry the war on terrorism next? Iraq, perhaps?

Hold on. Before we rush off to the next phase in our anti-terrorism campaign, we have to be sure the first phase is truly wrapped up. And, like it or not, the war in Afghanistan isn't over yet.

In fact, the endgame there may be much tougher than most Americans envision if the foreign members of the Taliban decide to fight to the death or if the Taliban reverts to guerrilla warfare in the rugged Afghan mountains, as some Taliban leaders have threatened.

Another complication: the intensifying power struggle already under way between members of the opposition coalition, the returning exiles, the Pushtun tribal militias and their respective foreign backers. We can't simply leave town and assume that whatever government sets up shop in Kabul will be an improvement over the Taliban.

Our challenge is to turn a rout into a decisive military victory and make sure that the post-war political structure that emerges prevents Islamic extremists such as the Taliban and bin Laden from returning to roost in Afghanistan. There are several steps we can take to make sure this happens.

The first may seem obvious, until you remember how the Gulf War played out: Apply relentless military pressure until the very end. This is no time to ease up on the beleaguered Taliban forces -- now's the time to deal them a mortal blow. They must be defeated soundly before they can burrow into the mountains and mount a sustained guerrilla war. We should not accept any face-saving deal that Taliban leader Mullah Omar negotiates with anti-Taliban Pushtun forces.

Some observers, believing our opponents to be beaten already, may consider this unnecessary. But Taliban diehards may hope to fight a "hit-and-run" guerrilla war similar to one the mujahideen (holy warriors) waged successfully against the Soviets in the 1980s. Yes, many of the Afghan Taliban have melted away, but they could regroup if the prevailing political winds change in Afganistan or Pakistan. U.S. forces and friendly Afghans must capture or kill the Taliban and al Qaeda before they can escape or settle in for guerrilla warfare.

After the leaders are brought to justice, American forces should be redeployed to other fronts in the war on terrorism, not tied down in an open-ended "peacekeeping" mission in Afghanistan. If introduced on a large scale, American troops could be denounced as an occupying force. This would allow surviving Taliban leaders or a successor movement to tap into Afghan xenophobia and Islamic zealotry.

We also should ensure that the Afghans become active stakeholders in the post-war reconstruction of their country, rather than passive clients of U.N. bureaucrats. Let's not repeat in Afghanistan the disastrous attempt by the United Nations to engineer the modernization of the clan-based politics of Somalia. Afghans fiercely guard their independence and could react violently if they think they've been reduced to a U.N. colonial mandate.

The last step is critical to building a long-lasting peace: Restore Afghanistan's historic role as a neutral buffer state and keep its neighbors from meddling in its internal affairs. If possible, the United States should negotiate a treaty with Afghanistan, its neighbors and Russia that would guarantee Afghan territory won't be used as a base to threaten any other state.

The notion of a stable Afghanistan may sound quaint to modern ears, but we should remember that it enjoyed nearly 50 years of stability, from 1930 through 1978, before external meddling disrupted its internal politics.

First, the Soviet-supported Afghan communists sought to impose totalitarian rule on a fiercely independent traditional society by force. Then the Pakistani-supported Taliban sought to impose its harsh Islamic extremism by force. Freed of outside meddling, there's a good chance that the Afghans could reach a consensus on how to share power, especially if they're rewarded with generous international aid for rebuilding their shattered nation.

And make no mistake: The Afghans must be the ones who do it. True nation-building can't be imposed from the outside. Others can help, but Afghans must be free to chart their own course for the future. Ultimately, only they can provide effective peacekeeping forces and keep their country from being re-infected with the virus of Islamic extremism.

James Phillips is a research fellow at The Heritage Foundation, a Washington-based public policy research institute.