Matt Yglesias, having decided to pay more attention to Afghanistan, finds himself confused about something:
One question I’m looking at somewhat hazily is this. If you read accounts of the Soviet war in Afghanistan in the 1980s, people generally always seem to think that American and Saudi and Pakistani support for the Mujahedeen was an important factor. I don’t see anyone saying “it was all a big waste of time and the same stuff would have happened anyway.” The Taliban has, as best as anyone knows, nothing remotely resembling that level of external support. So why isn’t that making more of a difference? Is our side actually much less effective than the Soviets were when you control for the change in external support?
Actually, that's usually presented as one of the big arguments for staying in Afghanistan and continuing the fight. Since the Taliban is relatively small and has only minimal outside support, it means they're eminently beatable. This isn't like Vietnam, where we were taking on half a million troops that had a superpower for a patron.
But I think the opposite is true. If the Taliban really is small and isolated, we shouldn't need a troop buildup. We should be able to beat them with 50,000 troops plus help from the Afghan army. The fact that we haven't after eight years — that, in fact, our progress has been negative over that time — suggests either (a) we have no idea how to fight them, or (b) they're more formidable than we think.
Neither of those is a good reason for withdrawing if we have a clear and well-articulated reason for staying, but I haven't heard it. Maybe it's in the reading list from Spencer Ackerman that's included in Matt's post. I'll take a look later today.