Weren't the Taliban hiding, protecting and giving comfort to Osama bin Laden when 9/11 went down? Didn't they continue that after we asked them to stop? If that doesn't make someone our enemy, I don't know what does.
Via The Daily Beast:
Look, the Taliban per se is not our enemy. That’s critical. There is not a single statement that the president has ever made in any of our policy assertions that the Taliban is our enemy because it threatens U.S. interests. If, in fact, the Taliban is able to collapse the existing government, which is cooperating with us in keeping the bad guys from being able to do damage to us, then that becomes a problem for us.