Stephen Walt offers a different interpretation of "cut and run":
One of the many dubious arguments now being invoked to justify an open-ended U.S. commitment in Afghanistan is the idea that withdrawal will damage U.S. credibility and cause other U.S. clients to doubt our staying power. It's possible that getting out would cause a few weak and vulnerable leaders to reconsider their reliance on the United States, but is that necessarily a bad thing? [...]
Instead of signaling a loss of American will, getting out of Afghanistan would remind other governments that the United States is not a philanthropic organization. Americans are willing to support competent and effective leaders whose interests are compatible with ours, but we are not in the business of endlessly subsidizing incompetence. In other words, we would telling friends and foes that we back winners, and we aren't inclined to waste resources on losers. So if you want our help, get your act together. What's wrong with sending that message?
Here's my worry. I understand entirely the perils - both strategic and political - of withdrawing from Afghanistan soon or adopting the Rory Stewart approach. If it appears the Pakistani army is serious in Waziristan, if some kind of halfway plausible national government emerges form the run-off, and if McChrystal can offer a credible plan for measurable progress within a year, then you can see why the administration appears to be leaning toward going deeper into the mire.
But there are some real questions here about the medium term.
It seems increasingly clear that Obama is going to give this war one more try, even if it requires a huge expenditure of political capital when he needs it all for healthcare. (That capital could, of course, win him some cover on the neocon right; but they will always turn on him whatever he does in due course. And it will be a perfect GOP angle to attack Obama both for being too interventionist and for being too weak. Internal logic has rarely bedeviled Republican partisanship in these fraught and loony period).