Andrew Exum outlines "five concrete ways in which policy makers, legislators and intelligence officials in Washington, DC can help the war effort in Afghanistan." His first one is "cut funding for the war":
This may seem a bit counterintuitive, to say the least. But right now, the massive amount of money flowing into Kabul is fueling the conflict. In a bizarre way, both the Taliban and the Afghan government currently have an interest in perpetuating this conflict: Both parties are making millions of dollars from the aid and development money saturating the country. These funds are distorting incentives and presenting ample opportunities for kickbacks, bribes, and other forms of corruption. It is little wonder Transparency International rates Afghanistan the world's third most corrupt nation.
The United States and its allies should only spend the money in Afghanistan they can properly manage and oversee.