Now that President Obama has announced his plan to “finish the job” in Afghanistan, how long might it be until we know if the new plan is working? The White House has talked about a sustained new level of effort for up to three years, but will it really take that long to know whether we have altered the momentum of the conflict?

In fact, by the middle of 2011 or so, we should know a great deal. Miracles are not likely, but major change should be visible. The simplest way to understand this is in the plan for improving Afghan security forces. While progress in the economy is clearly needed too, the first order of business is security.

Building an Afghan army and police force has accelerated already in recent years, and now the pace should pick up. In 2008, about 35,000 Afghan security forces were recruited and trained, a rate maintained in 2009. Afghan security forces number nearly 200,000 now, and NATO/international forces will soon total about 140,000. These are reasonable levels, given Afghanistan’s size. The new training capacity added in 2009 and early next year could result in about a quarter-million Afghan army and police by the end of 2010. With the expected NATO reinforcements, roughly 400,000 uniformed security personnel should be in place. That is getting to be a significant number, even if less than what some would consider ideal.

A more reliable Afghan force

Of course, these numbers will mean little if Afghan forces aren’t up to the job. In fact, much of the current police force isn’t up to snuff, so the U.S. trainers will effectively be starting from scratch for most of them. And if the new strategy works, we should see a rapid increase in not just the numbers of Afghan forces, but also their quality and reliability.

The Afghanistan government itself gives us reason for some optimism. Why? Next year, it will likely improve the pay and survivors’ benefits of soldiers and police. That’s a good start. But the main reason we’re hopeful is Gen. Stanley McChrystal’s emphasis on intensive mentoring and partnering of Afghan forces. After they are recruited and trained, Afghan police and army will now have NATO “sister units” working hand in hand with them. This goes beyond training and mentoring, in fact, to a form of intensive apprenticeship, even more systematic and intensive than was done in Iraq.

Such focused and close interaction brings other benefits besides training. It gives Afghans direct battlefield support when they are ambushed, for example. In addition, it helps U.S. forces pursue an anti-corruption agenda much more assertively than has been the case. When necessary, incompetent and corrupt leaders in the Afghan forces will be identified by integrated NATO forces so that they can be rooted out by Afghan officials (who are increasingly willing to do this). This will take time, but the benefits start to be apparent within 12-18 months. In Iraq, the national police were in very poor shape through 2006, but the firing and replacement of most of their leaders improved the situation drastically within a year.

Improvements in Afghanistan have already begun because of reforms of the Afghan police and army units started last year. To date, such steps have not nearly sufficed. However, now that U.S. trainers and mentors have begun to arrive in the combat theater in big numbers, and McChrystal’s concepts are being applied, the strategy has started to provide more fruits. The next complement of trainers will arrive in 2010. So based on this timeline, mid-2011 should be the key time to gauge progress there.

Do not expect uniform success in the next 18 months, though. In fact, Taliban and other resistance forces might step up their efforts, resulting in more attacks and higher casualties through 2010 and even into 2011. But in those provinces and districts where enough resources are deployed, we should be able to see progress in overall security indicators, in the happiness of the population with the government, in citizens’ sense of the quality of law and order in their neighborhoods. And gradually, the attacks, kidnappings, assassinations, civilian fatalities, and safety and usability of roads should improve. If they do not, something serious will be wrong, and we will have to face that reality directly and honestly.

The economic agenda

Economic improvements are needed too, of course. In the short term, commanders have funds at their disposal to help create jobs and some economic activity as soon as they clear areas of insurgents. An important additional element of our strategy is building up Afghan government capacity to establish a more sustainable economy. This will take longer than one to two years, admittedly. While tackling this challenge is important, even modest economic progress — combined with an improved security picture — could turn the tide of the war.

President Obama is taking a gamble with his new effort in Afghanistan. Though there is no guarantee of success, war-weary Americans and Afghans should at least know by mid-2011 whether the plan is succeeding.