The Taliban beat the Northern Alliance on the ground in the Afghan civil war. Even after oodles of US cash and loads of help from American military Karzai and the rump of the old Northern Alliance STILL can't stand up to the Taliban. It's time for us to stop supporting one tribal thug vs. another.
We kicked Al Qaeda's butt.That was the primary objective for involvement in Afghanistan. We've spend enough time trying to help the Afghans find a (more) peaceful means of sorting out out their issues. But they want to continue their bickering and engage in another civil war. So it's time for us to pack up and leave them to it.
If that's a "cut and run", so be it. Our tax dollars are better spent on other matters.