We had the right idea at first. We supported the Northern Alliance and they did most of the work.
The ANA will never be reliable. You cannot make a multicultural country out of Afghanistan. The ethnic militias are the only forces that can be relied on to be loyal to whatever the leadership directs.
They are like our National Guard or most of our soldiers in the Civil War where the men of each unit came from the same locality and their families all knew each other. Each man knew he and his family could never live it down if he were cowardly or disloyal.
We should forget about Karzai and give all support and power to local leaders. Led the local leaders create the level of government over them.