Khalilzad, who returned to the United States from nearly a month-long peace mission to South Asia and the Middle East, said on Friday that he had discussed conditions for the withdrawal of American forces from Afghanistan with the Taliban, but there had been no agreement on this issue yet, Dawn news reported.
Khalilzad said he has pressed the Taliban to agree to a permanent cease-fire as a step toward ending the war, but they have resisted, arguing that it would remove their leverage and reduce the Afghan government's incentive to make concessions in direct negotiations.
Mr Khalilzad last week announced a "draft framework" for a peace deal, though he warned that major hurdles remain.
And this can not be achieved without the help of regional players, in particular Pakistan, Special US Representative Zalmay Khalilzad said in his maiden public appearance before a Washington audience some six months after he was entrusted with this task by the Secretary of State Mike Pompeo.
Until a full agreement on such cease-fire terms is reached, he said, no part of the agreement would be instituted, ruling out a quick withdrawal of American forces from Afghanistan in the coming months.More news: Storm Erik Brings Wet And Windy Weather
A senior Taliban official said Wednesday that the United States has proposed to withdraw half of its troops from Afghanistan by the end of April, but the US military said it has received no orders to begin packing up.
Mr Khalilzad, who acknowledged that Pakistan had released a senior Taliban leader Mullah Baradar on his request to facilitate the peace talks, said that Pakistan could play a very crucial in the reconciliation process with the Taliban.
The Taliban control almost half of Afghanistan, and are more powerful than at any time since the 2001 US-led invasion after the 9/11 terror attacks in 2001.
Additionally, the Taleban have promised not to shelter foreign extremists, but experts say they can not be trusted and even now are helping to hide such militants.
"We will not just rely on people's words", he said, adding that there would have to be "enforcement mechanisms", which he did not define.More news: Greece backs Macedonia's North Atlantic Treaty Organisation accession
The Afghan Taliban has said that despite the ongoing talks with the USA and other regional powers, it had "not yet reached" any conclusion that would entail an immediate end to hostilities against America and its allies, according to a media report.
The Afghans, he asserted, must sit across the table with each other and come to an agreement about their future of their country. So, the time has come, they say for an inclusive dialogue leading to an inclusive piece, he said.
"They understand that they can not go back" to how things were, the U.S. negotiator said.
"We first and foremost have to put an end to the occupation and then focus on resolving our internal issues". Taliban officials alleged publicly this week that the United States had agreed to remove half of its troops from Afghanistan by May, a statement Khalilzad called false.
Recently, Taliban has appointed co-founder Mullah Abdul Ghani Baradar as the leader of their political office in Qatar to lead talks with the United States to end the Afghan war.More news: Spurs sink Leicester to stay in title hunt