What exactly are we doing in Afghanistan? Can someone tell me? Is it really to get Osama Bin Laden? Does he even matter anymore? Do we really care whether the Taliban run that country or not? The Taliban are not terrorists, determined to strike America. They're just Islamic fundamentalists, and is it really a major national interest of ours to install liberal democrats as rulers in Afghanistan? Will democracy even take hold or work in that wild country?
The 500 pound gorilla in the room is, I think, our desire to use Afghanistan as a pipeline territory to tranport the oil and natural gas from the Central Asians 'Stans' down to the Arabian sea and onto tankers for use in American and Europe (which is why NATO is also involved in Afghanistan). My gut level is that that is what we see as in our national interest, worthy of our investment in dollars and blood in the Afghanistan fight.
It's funny how the real reasons are never discussed. It would be too painful to see ourselves interfering in another country militarily for such crass reasons as oil and gas. But that's what we do all the time, of course.