Rufus Phillips, Vietnam expert, as quoted by the New Yorker:
I’m afraid the President, who seems like a supremely rational being, is trying to find the most rational policy option on Afghanistan, without thinking about whether it is feasible given political conditions on the ground, as well as who is going to implement it and how. What seems the most rational option here could be likely unworkable over there.
This is part of what happened to President Johnson during Vietnam. He relied exclusively on policy ‘experts’ who understood military and geopolitical strategy in the light of World War II and Korea, but who had no direct experience combating a ‘people’s war,’ while underestimating the North Vietnamese and misunderstanding the importance of the South Vietnamese, who were treated as bystanders. His advisers constructed strategies whose feasibility never got tested by those who knew Vietnam first hand. Pure reliance on the chain-of-command was disastrous in Vietnam because much of the most relevant information, the nuances which counted, could not be fully described in writing and were strained out as information flowed to the top. At a minimum, [General Stanley] McChrystal and [Ambassador Karl] Eikenberry, who have that first-hand knowledge, should be sitting in these strategy sessions.