To expand on my last answer a little bit more:
If you look at countries which have had democracy imposed on them (mostly in South America), I don’t believe that any of those countries were able to maintain a true democracy. Only Chile is now, finally, seeming to reach that state, if I recall correctly.
When you have a nation where all of the people are used to a dictator, head chieftan, etc., when El Presidente doesn’t step down at the end of his term he’s able to maintain his position due to various allegiances and bribes. The idea of Rule by Law isn’t something that has been passed down from one generation to the next for hundreds of years.
Even just looking at Russia, when democracy is attempted, most of the populace doesn’t like it. A democratic president doesn’t have the power to control the land, to fix all the issues of corruption that are probably left in his country. He must allow his rivals to work against him–which can be a great force where there is corruption and the military is still a political body rather than a group of simple government employees–and his legislature to slow him. There’s an uncertainty in the way the land is run–accepting of compromises–that the people are unused to and find unnerving.
Going from the world’s precedents up to date, I would very much doubt any real democracy being born if we follow our current course.
The local militaries need to be headed by known-to-be-honest Americans, cycled out regularly so that a culture of corruption doesn’t have time to leach in, promoting the locals who are honest and booting any who are not honest. Children need to learn about democracy in school, practicing mock-governments as part of their schooling, so that in ten to twenty years, a democratic government can actually be started that won’t simply revert to a dictatorship couched as a democracy.
Certainly this would take a great amount of effort, but at the same time it would be an investment that would almost certainly pay itself back. And more importantly, anything less is simply leaving the Afghani and Iraqi people to deal with cleaning up after us until the next time that we feel the need to go to war with their chieftan. Though, of course, as said, I would still only feel like I had any position to attempt just a radical investment in a foreign nation if it was agreed to by the people themselves.