Intelligent conservatives like former Sen. Chuck Hagel and Washington Post columnist George F. Will have publicly called at least for a reevaluation of America's goals in Afghanistan (the former) and in some cases for an end to the mission there (the latter). Liberals have been uncomfortable, if not adamantly opposed, with Obama's apparent willingness to extend the mission and to send in more troops.
It's understandable that, politically and intellectually, this is a tough nut to crack -- the hawkish right will call the president a coward and a quitter; the military will grumble that the mission isn't complete and that the US lives already lost cannot have been in vain; the insurgents will boast that America has shown a lack of fortitude as in Vietnam; future troubles in Afghanistan, as there are bound to be, will be laid at the feet of the Administration; and if there should be a large terror attack against the US, whether launched from Afghanistan or not, Obama will be tagged as an enabler -- but there are real lives at stake here, and whether American military personnel complain about the decision, their lives and sanity are in the president's hands and must be safeguarded whether they approve or not.
Further, all sides recognize the paramount importance of Pakistan in the whole terrorism house of cards. American foreign policy has to focus on how to best stabilize that country, which possesses nuclear weapons that cannot be allowed to fall into the wrong hands. (I would start by intensively brokering a relaxation of tensions between Pakistan and India, which is domestically Pakistan's biggest security concern. We have pull with India. Show some American good will while freeing up Pakistani resources to secure the northwestern tribal areas.)
But the reality here is that eight years into the US mission in Afghanistan, it looks more and more like the oft-repeated historical lesson about invading the central Asian nation (the British failed; the Soviets failed; no one can do it) is more true than not. I'm not saying that all the answers are clear here, but I am saying that diverting more blood and treasure to Afghanistan at this time now seems pointless, and it is time to get out.