From Andrew Exum at Foreign Policy
U.S. President Barack Obama, who carried out an otherwise responsible review of U.S. strategy in Afghanistan in the fall of 2009, blundered when he publicly announced that the United States would begin a withdrawal from Afghanistan in July 2011. Within the ranks of Afghanistan's insurgent groups and even among our allies and the civilians in the country, this date was interpreted to mean that a total withdrawal of U.S. and allied forces was imminent. No insurgent group, to paraphrase defense analyst Stephen Biddle, was about to accept a loaf of bread when the bakery was on offer. Why would the Taliban and other insurgent groups negotiate when the United States was on its way out already?
The problem of Afghanistan's varied insurgent groups also complicates reconciliation talks. Of the three principal insurgent groups, only Gulbuddin Hekmatyar's Hezb-i-Islami Gulbuddin (HIG) might be considered ripe for any kind of reconciliation with the government in Kabul. But the HIG is arguably the least significant of the major insurgent groups, and even then, Gulbuddin himself would not likely be allowed to play a role in an Afghan government.
Of the other two groups, the Haqqani network, under the leadership of Sirajuddin Siraj Haqqani, maintains strong ties to al Qaeda and is considered more or less irreconcilable, while the Quetta Shura Taliban is thought to be reconcilable only if Mullah Mohammed Omar himself approves of the reconciliation process. The insurgents in Afghanistan are no more unitary an actor than the Afghan government or the NATO coalition, further complicating negotiations.
More here.