British MP Rory Stewart writing this week about western military policy towards Afghanistan:

We can do other things for Afghanistan but the West – in particular its armies, development agencies and diplomats – are not as powerful, knowledgeable or popular as we pretend. Our officials cannot hope to predict and control the intricate allegiances and loyalties of Afghan communities or the Afghan approach to government. But to acknowledge these limits and their implications would require not so much an anthropology of Afghanistan, but an anthropology of ourselves.
The cures for our predicament do not lie in increasingly detailed adjustments to our current strategy. The solution is to remind ourselves that politics cannot be reduced to a general scientific theory, that we must recognize the will of other peoples and acknowledge our own limits. Most importantly, we must remind our leaders that they always have a choice.
That is not how it feels. European countries feel trapped by their relationship with NATO and the United States. Holbrooke and Obama feel trapped by the position of American generals. And everyone – politicians, generals, diplomats and journalist – feels trapped by our grand theories and beset by the guilt of having already lost over a thousand NATO lives, spent a hundred billion dollars and made a number of promises to Afghans and the West which we are unlikely to be able to keep.
So powerful are these cultural assumptions, these historical and economic forces and these psychological tendencies, that even if every world leader privately concluded the operation was unlikely to succeed, it is almost impossible to imagine the US or its allies halting the counter-insurgency in Afghanistan in the years to come.  Roman Emperor Frederick Barbarossa may have been in a similar position during the Third Crusade.  Former US President Lyndon B. Johnson certainly was in 1963. Europe is simply in Afghanistan because America is there. America is there just because it is. And all our policy debates are scholastic dialectics to justify this singular but not entirely comprehensible fact.