As the country and world await President Obama's decision about how fast to pull U.S. forces out of Afghanistan starting next month, it is worth understanding the implications of different possible drawdowns for the strategy there. Much of the current policy debate is very general, relating the number of American forces to the degree of U.S. interest in Afghanistan, or the remaining terrorist threat after the death of Osama bin Laden, or the budget situation in the United States. While these considerations are not irrelevant, it is also important for members of the public and Congress to have a sense of what various scenarios would imply for the official civilian-military campaign plan inside of Afghanistan itself.

The typical American consumer of the daily news may be forgiven for thinking of the war in Afghanistan as simply a sand trap sucking up hundreds of billions of dollars and tens of thousands of troops while taking thousands of American lives—with little more than frequent suicide bombings and reports of corruption in Kabul to show for the effort. In fact, the war's course has been extremely difficult. Even relative success (defined as a future Afghan government that can control most of its territory with little outside help) is hardly guaranteed. But there is a campaign plan, and it has a considerable logic behind it—as well as growing evidence to suggest it is working.

In a nutshell, the campaign plan might be summarized as this: In 2011, consolidate increasingly secure areas in Afghanistan's south while fending off the expected Taliban counteroffensive which, though likely to be hamstrung by all the NATO/Afghan government progress of last year, may yet be potent. As we have continued to see all year, assassination campaigns and spectacular bombings can be expected to pose particular threats even if overall battlefield dynamics are turning the way of coalition forces from Kabul to Kandahar to Helmand. In 2012, increasingly turn over responsibilities for security in the south to rapidly improving Afghan army and police forces while bolstering U.S. efforts in the country's east. In 2013 and 2014, accelerate foreign-troop drawdowns as Afghan forces reach full size and capability and as the insurgency has hopefully been considerably weakened. Throughout the period, continue to work on Afghan economic development and government capacity while supporting President Karzai's efforts at realistic peace talks with the Afghan opposition.

There are still weak links in the strategy, especially at the political level, where Washington is having a hard time motivating Pakistan to go after insurgent sanctuaries on its soil and where we lack an adequate plan for supporting Afghan political development as the country moves towards 2014 presidential elections to replace Karzai. But the military effort is increasingly sound—and increasingly showing results. Among the bumper-sticker signs of progress in the country's south: at least 10 percent more Afghans consider roads secure than did so a year ago, most government officials in the south now travel by road rather than NATO helicopter, the number of schools open in Helmand province has increased by almost half, Afghan army and police contributions to combined offensives in the south now constitute about 50 percent of all necessary coalition forces and poppy production over the last three years has been cut in half.

So how would different drawdown trajectories for American forces affect the campaign plan? The above approach implies only very modest reductions in U.S. forces over the next year or so—perhaps a couple thousand this summer, mostly in support units; perhaps a couple of battalions this winter, once the fighting season is over; substantial reductions only in late 2012 and beyond, as next year's fighting season winds down (with a lot of progress to show by then, hopefully, in Afghanistan's east as well as south, and the Afghan security forces nearing full strength). In numerical terms, I might estimate the numbers as 97,000 U.S. troops by the end of this summer, 95,000 in early 2012, 75,000 in late 2012, and then 50,000 in late 2013 and 25,000 in late 2014. These numbers are admittedly rough.

Consider two other options. First, in keeping with what Leslie Gelb has recently described as a possible administration option, require the "second surge" of U.S. forces in Afghanistan to come home by roughly the end of 2012, meaning that our troop numbers might total around 68,000 at that point. (Better yet, give commanders the whole winter of 2013 to do this drawdown so there is no rush for the exits in November and December.) But leave details of the drawdown to American commanders. This approach is broadly consistent with the campaign plan as I have tried to summarize it above—perhaps a bit faster and steeper of a drawdown than might be entirely consistent with the strategy, but not too far off.

Second, and more of a departure from current strategy, return U.S. forces in Afghanistan to 68,000 by the end of 2012 but also require a significant cut this year—say to 85,000 GIs by Christmas. This approach would require two major changes in the campaign plan as I currently understand it. One change is that substantial numbers of U.S. forces would have to be withdrawn from southern and southwestern Afghanistan even in the course of this year's fighting season. That might be ok if the Taliban prove weaker this year, after all the Afghan-ISAF offensives of the last two years in Kandahar and Helmand in particular, but it still requires a rapid transition at a time when Afghan forces in the south are only beginning to materialize in the quantity and quality needed. At a tactical military level, it is quite risky. Another change is that we could not reinforce existing capabilities in the east. The east of Afghanistan has three times the population of the south and southwest combined, but roughly equal numbers of foreign forces today. Ideally, we would swing another brigade or so to the east later this year to help with the mission there, allowing 2012 to become a true turning point in the campaign in places like Khost, Paktia and Paktika. Without those added forces, progress will likely be much slower, as it will have to await the gradual strengthening of the Afghan army and police.

At a political level, more rapid drawdowns could perhaps place some additional and potentially useful pressure on politicians in Kabul to get their acts together. But it could complicate our dealings with Islamabad, which might view an accelerated drawdown plan as just the latest proof that Americans are yet again rushing for the exits in Afghanistan before the job is done. On balance, I think it would be a mistake. Much better to stick with the logic of the campaign plan as it exists—which already allows for rapid downsizing come late next year, if we can be patient until then—and which increasingly shows promise on the battlefield.

Image by the U.S. Army