I have broached the issue a few times here and elsewhere. An amazing number of people simply declare that President Gore would have caught the terrorists before 9/11. Then they sit back and smile. End of problem. Details on that tend to be a bit fuzzy.

I suspect that if Gore had needed to respond to 9/11, he would have used the approach on Afghanistan that Clinton used on Bosnia and Desert Fox: A bombing raid from altitude. In fact, that's what we did do in Afghanistan for over a month before the first major (non-special forces) ground troops went in.

The problem with that is that such tactics are designed to attack facilities, not a small group of people. Small groups of people can be extraordinarily resistant to air raids if they're prepared at all, usually by arranging to be elsewhere. We failed to get Saddam with precision targeted bombing attacks. Come to think of it, we bombed the living shit out of Germany in WWII and didn't get Hitler that way either. If all it took was an air attack to keep bin Laden from slipping into Pakistan, the pounding we gave Tora Bora from the air would have worked.

So, at some point it would either have been bomb the terrorist bases and go home, and wait for the Taliban and al Qaeda to drift back out of civilian enclave hideouts (then do it again?), or bring in the ground troops for the serious clearing and holding needed.

There is no easy way to fight this kind of a war. We thought there was at first--take out enough bad guys and the rest of the population will do the rest. You don't get a bunny rabbit by cutting the head off a snake. You get a snake with no head writhing around. And sometimes a new head grows back.

Eventually, the forces that poured into Iraq to confront us would have poured into Afghanistan as well. The only difference is that the terrorist ratlines would have been from western Pakistan and Iran instead of Syria and Iran. That's not even counting the various "-stans" on the northern border.

Afghanistan would been as hard a fight as Iraq. It's bigger, has a larger population, is far more rugged in terrain, has no ground routes into the country from friendly nations, and is more tribal and primitive than Iraq.

There aren't any easy answers in any alternate history.