One interesting thing about the past few decades of world history is that essentially the exact same events can be read as having precisely opposite implications. Here, for example, is Peter Bergen arguing for more forceful American military intervention in Afghanistan:
The implication of Walt’s objection to the ramped-up Obama strategy in Afghanistan is that the U.S. should either do less in Afghanistan, or even just get out altogether. But America has already gone down this road. Twice. In 1989 the U.S. closed its embassy in Kabul and then effectively zeroed out aid to one of the poorest countries in the world; meanwhile Afghanistan was racked by a civil war, which spawned the Taliban who then gave safe haven to al Qaeda.
Then in the winter of 2001 the Bush administration overthrew the Taliban, and because of its aversion to nation-building rebuilt the country on the cheap and quickly got distracted by the war in Iraq. Into the resulting vacuum stepped a resurgent Taliban. This time the movement of religious warriors was much more closely aligned with al Qaeda.
There is, of course, something very arbitrary about starting this clock in 1989. One could just as easily note that in 1980 the United States decided that it would serve our interests to deliberately destabilize Afghanistan by trying to foster a series of links between Saudi financing, Pakistani intelligence, and Afghan religio-nationalist militants and that we’ve spent much of the past ten years coping with the unintended consequences of this activity.
Which I think it’s why it’s worth being above-board about the fact that people really come to this discussion with some pretty strong ideological priors. I think there’s a view of the world out there which looks at the American military as a kind of balloon that ought to expand to fill every vacuum that arises in the world. There’s another view which finds this trend in our recent foreign policy alarming. I’m much more in the latter camp. And I think that what Bergen is really showing here is that we have no practical ability to actually fill these voids on a sustained basis and that, therefore, the practical results of vacuum-filling enterprises are dominated by the unintended consequences.