Right now, the United States needs to draw down our troops to about 20,000. We need to clarify the mission to a narrowly focused military mission against the Jihadist infrastructure and an intelligence operation designed to counter the influence of both the Jihadists and the Russians. Then we need to stay, and stay forever.
This is a sustainable mission. The Afghans will respect a long term presence of 20,000. Americans, outside of the progressive Left and their useful idiots on the Ron Paul psuedo-Right, do not oppose overseas military operations; we oppose pointless casualties.
The United States has two major interests in Afghanistan: to prevent the re-emergence of Afghanistan as a training/planning ground for Jihadists and to counter Russian influence in Central Asia; Afghanistan offers us an under appreciated opportunity to raise hell in Vladimir Putin's backyard.
Current U.S. policy in Afghanistan is the result of a Bush-Era Democrat talking point that was bogus then and remains so today. Whether making Afghanistan a better place was always a naive impossibility, or if the current situation is due only to Obama's lack of commitment and rules of engagement, the fact remains that changing Afghan society no longer passes any rational cost-benefit analysis and it isn't a core American interest (if it ever did or was).
The United States secured most of our national interests in Afghanistan within a year of the initial invasion; we only need about 20,000 (or so) troops to maintain that security and provide a future base of operations should the situation with the Jihadists or Russia change.
Some will argue that we should leave entirely because the Jihadists and Russains will leave us alone if we leave them alone. This is nonsense; Vladimir Putin and the Jihadists don't want to be left alone, they want to dominate the globe. They're going to play that game whether we like it or not. In the book 48 laws of Power author Robert Greene addresses this tiresome argument in Law 18: Do Not Build Fortresses to Protect Yourself – Isolation is Dangerous:
The world is dangerous and enemies are everywhere – everyone has to protect themselves. A fortress seems the safest. But isolation exposes you to more dangers than it protects you from – it cuts you off from valuable information, it makes you conspicuous and an easy target. Better to circulate among people find allies, mingle. You are shielded from your enemies by the crowd.The Jihadists and Vladimir Putin are going to work against us regardless of what we do; failure to accept this reality and take effective countermeasures is national suicide....