From RAND Corporation:

In the first few days of 2012, the Afghan Taliban confirmed in an email to media outlets what had been whispered about for weeks: that a tentative agreement had been reached to open an office in Qatar from which to engage in preliminary peace negotiations with the U.S.-led coalition. The move drew criticism for cutting the Afghan government out of the loop and for lending legitimacy and influence to the Taliban even as it continued carrying out serious attacks. However, it also represented the first important step toward the near-universally accepted reality that any resolution in Afghanistan would occur at the negotiation table and not on the battlefield.