Sometime over a year ago, I was arguing with a conservative about the war in Iraq. It was becoming clear that the "surge" was achieving more than I would have expected in terms of calming the level of violence over there. But, I argued, even that unanticipated success didn't change the fact that the whole endeavor was a waste of time, resources, and personnel that would be better spent in Afghanistan. My line mirrored that of Barack Obama and most mainstream Democrats. But my interlocutor had an interesting reply. He told me that if the left had its way on Iraq, we would shortly find ourselves losing faith in the war in Afghanistan as well. The impulse to withdraw, he said, would become irresistible.

At the time, it struck me as a wild and implausible theory. I knew my own heart. The war in Afghanistan was completely different—undertaken for the legitimate purpose of responding to the 9/11 attacks, supported by a broad multilateral coalition, and popular with the people of Afghanistan to boot.

The reasons being given for the Obama administration’s new commitment to the Afghanistan campaign have a distinct air of quagmire about them.

Yet for all my confidence at the time, it looks more and more to me as if I was wrong and he was right. A weekend New York Times story by James Dao showed the difficulty antiwar organizations are having in mobilizing support for a campaign against continued American military involvement in Afghanistan. The reasons are easy to understand; the war in Afghanistan is better-founded than the war in Iraq, and the president undertaking it much better-liked by the left wing. But instead of taking advantage of his moment of political opportunity to try to put the campaign in Afghanistan on a sustainable basis, the administration appears to be contemplating a serious escalation of the effort that will ultimately polarize public opinion and push more people into the antiwar camp.

The easiest signpost on which to hang this change is the increasing number of American soldiers serving in Afghanistan. But the larger issue is the steady redefinition of the purpose of the mission; what Michael Cohen at the blog Democracy Arsenal has termed "Afghanistan mission creep." Rather than a limited mission to fight al Qaeda and support the existing Afghan government, we seem increasingly drawn into a hazily defined effort to reconstruct Afghan society so as to create a stable unitary government. If the issue here were simply that Hamid Karzai lacks certain things that the United States has in abundance—money, guns, air support—then this might be a reasonable objective. But in reality, Karzai is missing things we have no clear way to provide—things like political legitimacy and an ability to deliver on the rule of law. Thus, rather than provide a degree of military support to the Afghan government, we're essentially planning to try to govern Afghanistan ourselves while getting into quarrels with Karzai over allegations of election fraud and his new vice president's involvement in drug smuggling.

What's more, the reasons being given for this new commitment have a distinct air of quagmire about them. Secretary of State Hillary Clinton opined that "to withdraw our presence or keep it on the low-level limited effectiveness that had been demonstrated would have sent a message to al Qaeda and their allies that the United States and our allies were willing to leave the field to them." Bruce Riedel, who helped head an Obama administration review of Afghanistan policy, told an audience at the Brookings Institution that we can't leave because "the triumph of the jihadism of al Qaeda and the Taliban in driving NATO out of Afghanistan would resonate throughout the Islamic world." In other words, we can't leave Afghanistan until we've killed every single person who wants us to leave the country.

This is not only perverse, it's weirdly detached from any practical considerations about mitigating the threat from al Qaeda; a threat that, after all, doesn't exclusively manifest itself in Afghanistan and that's likely to grow in its global aspects if the United States settles into an indefinite occupation of another Muslim country. Thus, though I'm reluctant to describe mysef as "against" the war in Afghanistan, I find myself increasing in alliance with an "antiwar" point of view as the scale of the operation grows and its strategic underpinnings come to resemble Dick Cheney's arguments about Iraq.

What the antiwar movement lacks at this point is much in the way of leadership. Thus far, only Senator Russ Feingold of Wisconsin has truly taken up the cause and he's a bit of a niche product among left-wing activists, lacking either a major national profile or a post on the Armed Services Committee from which to influence policy. What's more, the American media has a double standard with regard to dog-bites-man stories on issues of war and peace. Hawks calling for war make news, but longtime doves like Feingold are considered to lack "credibility" when arguing against it. Additionally, for the moment, outside progressive organizations with a multi-issue focus would rather not touch Afghanistan with a 10-foot pole when they could be cooperating with the administration on health care and energy issues.

Obama has, in other words, a pretty open grace period in which complaints from the left about his Afghanistan policy will remain fairly marginal. In principle, the administration could take advantage of that opportunity to try to shift our approach to that country in a more sustainable direction—an essentially defensive mission aimed at ensuring the Afghan government is strong enough to avoid a Taliban takeover of the country, hoping that would prevent the re-emergence of the openly operating terrorist training camps of the pre-9/11 era. Instead, the administration is choosing to escalate, both the level of commitment and the nature of the mission. They'll be able to do it for now, but this path all but guarantees an increasingly polarized debate that increasingly pushes liberals into the antiwar camp. Given time that, in turn, will drive groups like MoveOn.org and the more left-wing members of Congress to become increasingly vocal. Such a path risks an LBJ-in-Vietnam scenario; one that could turn even more ugly in the event that Obama proves less successful than Johnson in actually delivering the goods on domestic policy.

For the moment, though, Obama is safe. It's not yet too late to turn the policy trajectory around and avoid a nasty showdown with his base.

Matthew Yglesias is a fellow at the Center for American Progress Action Fund. He is the author of Heads in the Sand: How the Republicans Screw Up Foreign Policy and Foreign Policy Screws Up the Democrats.