Advocates of a swift withdrawal tend to see Biden as their ally, and in a sense they’re right. His plan would reduce America’s footprint in Afghanistan, and probably reduce American casualties as well.

But in terms of the duration of American involvement, and the amount of violence we deal out, this kind of strategy might actually produce the bloodier and more enduring stalemate.

It wouldn’t actually eliminate the American presence, for one thing. Instead, such a plan would concentrate our forces around the Afghan capital, protecting the existing government while seeking deals with some elements of the insurgency. History suggests that such bargains would last only as long as American troops remained in the country, which means that our soldiers would be effectively trapped — stuck defending a Potemkin state whose leader (whether Hamid Karzai or a slightly less corrupt successor) would pose as Afghanistan’s president while barely deserving the title of mayor of Kabul…

The bleakness of this Plan B is the best argument for giving our military the time it needs to try to make a counterinsurgency succeed. We can’t hold the current course indefinitely, and we won’t: President Obama’s decision to set a public deadline was a mistake, but everyone knows there are limits to how long the surge of forces can go on. But of the options this White House seems willing to consider, it’s the one that holds out hope of enabling a real withdrawal from Afghanistan.