The US negotiator on Afghanistan on Monday said he was optimistic that the Taliban and government would begin peace talks. And Zalmay Khalilzad said US President Donald Trump could pull out American troops early if all went well. The Afghan government has been hastening the release of prisoners, a key condition for the Taliban, after a ceasefire for the Eid Al Fitr holiday and a continued lull in fighting. "There's been a lot of progress in the past few days," said Mr Khalilzad, who negotiated a deal with the Taliban under which Washington plans to end its longest war. "A lot of people have been pessimistic that we could get to this place where we're discussing where and when inter-Afghan negotiations would begin and that there would be enough progress on the prisoners issue." But he did not set a date and warned that "still more needs to be done" on freeing prisoners. Mr Khalilzad told reporters that 2,400 to 2,500 Taliban prisoners have been released since a peace agreement with the Taliban in February, compared with some 400 prisoners released by the Taliban. He said the US hopes "that violence will stay at very low levels before intra-Afghan negotiations begin, and those negotiations will determine and decide on a comprehensive and permanent ceasefire in Afghanistan." Abdullah Abdullah, who heads the government council for the talks, said on Saturday that he was ready for talks "at any moment." Under the agreement with the Taliban, the US will pull troops out of Afghanistan by mid-2021 in exchange for the insurgents' commitments to keep out Al Qaeda and other foreign extremists. Mr Khalilzad said ISIS "is a fact of life in Afghanistan" but that both the Afghan government and the Taliban are fighting the group. He said if the government and the Taliban cooperate on a "political roadmap", both sides would emerge "in a much stronger position to pursue the fight against ISIS until ISIS is eliminated in Afghanistan." US officials have said the withdrawal is already ahead of schedule because of coronavirus concerns. <em>The Wall Street Journal</em> reported last week that the Pentagon had drafted plans for troops to leave late this year, coinciding with the US presidential election. Mr Khalilzad said the withdrawal was "the prerogative of the president, and if he thinks that the conditions have been met then we could do it faster, but the key thing is whether the conditions have been met". The US invaded Afghanistan in 2001 and toppled the Taliban regime, which welcomed Al Qaeda after the September 11 attacks. A recent expert report to the UN Security Council said Al Qaeda and the Taliban "remain close" and were in regular consultations over the negotiations with the US. Mr Khalilzad played down the report, saying it largely covered a period before the February 29 deal signed in Qatar. "There is progress but we will continue to monitor those activities very closely," he said of Taliban ties with Al Qaeda.