The Afghan government needs to see Pakistan make "tangible progress" on pledges to use its influence to help end the Taliban insurgency, a foreign ministry spokesman said Sunday. The statement came a day after Afghan President Hamid Karzai said he was giving up on trying to talk to the Taliban directly and that the key to ending the war is mediation by Pakistan. It underscores the Afghan officials' deep frustration over their inability to deal with a major barrier to ending the war in Afghanistan - insurgent havens across the border in Pakistan. Already tense Afghan-Pakistani relations have been further degraded in recent weeks as U.S. and Afghan officials have publicly blamed the Pakistani government for supporting the insurgency in Afghanistan following a string of high-profile attacks. "Afghanistan has invested a great amount of goodwill and political capital to create an atmosphere of trust and confidence and to try to improve relations with Pakistan over the past three years," the spokesman, Janan Mosazai, told reporters in Kabul.