Tim questions whether I can really discern the true motives behind Obama's support for an escalation of troop levels in Afghanistan. The short answer is no, I'm not a mind reader. But I disagree with Tim's point that an Obama reversal on the subject "wouldn't be a hard sell". Voters may be ambivalent on Afghanistan, but they're equally ambivalent on Obama's ability to handle national security issues. The popular support for withdrawal from Iraq isn't present with Afghanistan.
It still seems like a qualification for being "commander-in-chief" in this political/media climate includes holding hawkish views on foreign policy issues, which is why so many Democrats with presidential hopes voted for the Iraq war in the first place. I'm not sure that's fundamentally changed, so I can't imagine Obama changing his mind during the campaign, and I think in some ways it would be even more difficult for him to do so afterwards.
But like I said, I'm also not convinced an escalation would be a bad move, if accompanied by the kind of diplomatic effort recommended by Kaplan. Kaplan says Obama's support for more troops "in danger of conceiving of war in narrow military terms alone," but the foreign policy vision Obama and his advisers have laid out suggests that isn't the case.