President Obama is scheduled to announce his Afghan troop withdrawals on Wednesday night. The Los Angeles Times  reports  he will bring 10,000 troops home by the end of the year and the remaining 20,000 surge personnel by the end of 2012. I have no idea if that’s accurate, but if so that would be a steeper reduction this year than our military commanders feel comfortable with. At the same time, it would allow them flexibility in managing the drawdown and would keep two-thirds of the surge forces in Afghanistan through the 2012 summer fighting season.

If that is in fact what Obama announces–or some approximation thereof–it won’t be catastrophic. But nor will it be great. It will force the remaining troops, whose numbers are barely adequate at the moment, to assume an even greater level of risk.

What, I wonder, is the imperative, either strategic or political, that forces Obama to do this? Why announce any drawdown at all? Or why not announce only the most minimal drawdown?

I realize the country is war weary, and the conflict in Afghanistan is not popular. But will it really be any more popular if we have only 90,000 troops there–or even 70,000–instead of 100,000? I doubt that will make any difference in terms of popular opinion. But it could make a big difference on the ground where commanders are already struggling to police a vast swath of geography against Taliban incursions. Kandahar and Helmand provinces have a critical mass of troops now, but not so in Regional Command-East where the Haqqani Network and other terrorists are still able to operate. Pacifying the east will require at least another campaigning season–and probably more. This troop reduction will make that task all the more difficult.

This drawdown could jeopardize the success of the entire operation and has the potential to be a huge political setback for the president.  He will be judged ultimately not on how fast he withdrew forces from Afghanistan but on what kind of Afghanistan he left behind. I would think, therefore, that having committed himself to the war effort already, it would be in his interest to do everything possible to see it through, notwithstanding the political criticism he might incur along the way.

Certainly Congress will not force his hand. Republicans may be growing more isolationist; they are especially wary of the Libya intervention. But there is not much opposition among Hill Republicans to the war in Afghanistan, and no real attempt to mandate steeper troop reductions. Left-wing Democrats would like to see a faster pull-out, but Obama is their guy, and they don’t have enough support to make him do something he doesn’t want to do.

So again, what is driving Obama here? If it’s not strategy and it’s not politics, I have to believe it’s his own ambivalence about the mission. This also helps to explain why, in spite of his willingness to send reinforcements to Afghanistan, he has rarely made the case for the war effort publicly. He seems almost embarrassed by his own commitment. Certainly he has not embraced the role of a wartime commander-in-chief. I only hope his doubts and hesitations do not put the entire war effort at risk.