Robert Kaplan tries to make sense of it here. Very bothersome to think about China just waiting and watching us waste lives and treasure there.
From Foreign Policy.com:
We wouldn't intervene if we were starting from scratch today, but some will say that allowing ourselves to be defeated by the Taliban will have disastrous effects on our reputation and encourage bin Laden & Co. to believe they are winning. Robert Kaplan takes this line in an op-ed in today's New York Times, arguing that "an ignominious withdrawal from Afghanistan is precisely what would lead to our decline, by demoralizing our military, signaling to our friends worldwide that we cannot be counted on and demonstrating that our enemies have greater resolve than we do. That is why we have no choice in Afghanistan but to add troops and continue to fight."
This is an familiar line of argument, of course, even though the best scholarly studies of reputation and credibility have found that past behavior doesn't have much effect on future credibility. Be that as it may, one could just as easily argue that U.S. credibility will be damaged far more if we squander another trillion dollars in Afghanistan and end up with a degraded and demoralized military and a population that is truly sick of overseas involvements.