It depends on the objectives. If it is the Bush, do nothing strategy then its like Viet Nam. But if the idea is to get Al Qaeda whey they live and enough resources are committed to do that, after a year or so our only mission will be to help rebuild the country.

When the Russians were in Afghanistan the whole country was against them along with foreign fighters and Charlie Wilson's supplies. The Taliban and Al Qaeda are a much smaller group with much less support.