Anatol Lieven in the NYRB blog:
The attempt at talks between the United States and the Afghan Taliban appears to have broken down for the moment. This is not unexpected, and is not in itself cause for despair. Almost every negotiating process in history aimed at ending insurgencies and civil wars has taken a very long time, and encountered numerous reverses along the way. Things are especially difficult because the conflict is not simply an insurgency against an “occupier,” but also a civil war between local groups, with one of them supported from outside. This means that negotiations have to be between three or more parties—the US, the Taliban, the Karzai government, and other anti-Taliban forces.
This kind of negotiating situation is not new: it was true in Northern Ireland, which involved the British, the IRA, and the Ulster protestant parties; in Algeria with the French government, the FLN and the French settlers in Algeria; and in Vietnam with the US, North Vietnam, and South Vietnam. Of course, one solution is for the outside power simply to abandon its local allies and reach a settlement with the enemy without them (of course, with face-saving provisions, but with the implicit understanding that these allies are being thrown to the dogs). This is what the insurgents always aim at—and what in Algeria and Vietnam they eventually achieved, after immense bloodshed: splitting the foreign power from its local allies or proxies. And this is precisely what Karzai and his supporters fear most, accounting for the sometimes hysterical nature of their protests against negotiations with the Taliban.
Seen from Kabul, there are good reasons to fear that the US will negotiate some sort of deal with the Taliban and quit Afghanistan entirely.