Once Clinton won the presidential election with his understanding that "it's the economy, stupid". It might help when the US realizes that in Afghanistan too.
Yet the US is mostly committed to "institution building". It is vigorously expanding Afghanistan's army and police and investing in things as diverse as education, justice and agricultural education. The problem is that it looks like everything will bring down again once the US departs.
I would prefer a different development approach that builds on what our modern world has to offer:
- build roads and take care to have good connections between Afghanistan and its neighbors. Look also at Indian Ocean ports and connections to Russia.
- mobile phone is a big success in Afghanistan. Make sure it is everywhere available.
- extend the other modern media - television and radio - too. And use them also for education: alphabetization, a regular school curriculum, agricultural extension, etc.
- find industrial products in which Afghanistan might specialize for export and stimulate that people will actually produce them. One might even build model factories to get started. Make sure there are no barriers: no red tape in Afghanistan and no trade barriers in the US and other potential export markets.
This would also include a safety policy that gives priority to the cities and the roads connecting them while relying on local leaders and tribes to keep the villages safe. Unfortunately the US still equates all types of local militias with warlords (and is encouraged to do so by Karzai who likes to have a power monopoly). As a consequence the US is relying on the rather weak Afghan army and wasting its time in the province while leaving Kandahar to Karzai's mafia brother and the Taliban.
I see the Afghan conflict primarily as an ethic conflict. The Taliban was an Pashtun organisation. The US conquered Afghanistan with the help of the other tribes but as afterwards turned on them and chose for a Pashtun president with extensive powers. In the mean time it accused the leaders of the other tribes of war crimes and doing so disqualified them for a position of power. I don't agree. Those war crimes were clearly acts of inter-ethnic revenge. Dostum let some Taliban die locked up in containers that were left in the sun. But the Taliban had done the same with its adversaries. And while the Hazaras killed dozens of Pashtun the Taliban had killed thousands of Hazara. I don't approve such revenge, but given that there hasn't been any action to make the Taliban accountable for its deeds I don't think we should use it to disqualify those other ethnic groups.
Having disqualified the leadership of the other tribes Karzai is now handing them over to his fellow Pashtun - the Taliban - by forbidding those tribes to defend themselves. In the mean time the US is buying his nonsense about institution building and that all local militias should be strictly subordinate to the army.
Where the play of Karzai leads is clear. His brother in Kandahar has no trouble at all to collaborate with the Taliban and one can expect that Karzai will find a similar way to collaborate with his fellow Pashtun. But he has a delicate hand to play: he is from a minor tribe and his main card is that he is the president. It is for that reason that Karzai has reacted vehemently towards any sign of direct negotiations between the Taliban and the US. That would rob him of his pivotal position.