The US special representative for Afghanistan, Zalmay Khalilzad, held talks in Qatar this week with leaders from the Taliban and the Afghan government to try to speed up peace negotiations.
US State Department spokesman Ned Price on Thursday said Mr Khalilzad stayed in Doha for more talks on advancing negotiations between Kabul and the Taliban.
Mr Price said the envoy was also pushing for a reduction in violence in Afghanistan.
He said Mr Khalilzad would also meet members of the international community “to see how best to accelerate the peace process".
The Taliban said on Wednesday that Mr Khalilzad met their senior leader, Abdul Ghani Baradar.
“The complete execution of all articles of the Doha deal was debated and both sides stressed adherence to the agreement,” tweeted the militant group's spokesman, Mohammad Naeem.
Mr Naeem called for the withdrawal of “foreign forces according to their deadline”.
The Trump administration agreed to pull the remainder of US troops out of Afghanistan by May 1, but the Biden administration has not committed to this deadline.
"It's going to be hard to meet the May 1 deadline just in terms of tactical reasons," US President Joe Biden said last week. "It's hard to get those troops out."
The US has 2,500 troops in Afghanistan but is looking at brokering a political settlement between the Taliban and the government in Kabul that would allow them to leave.
The agreement, which involves a reduction of violence and elections, has not been put in place yet. This video details where the peace deal stands a year after it was signed.
But the State Department hopes a conference in Istanbul, Turkey, will help to make progress on intra-Afghan talks with help from the international community.
Before his Doha stop, Mr Khalilzad was in Turkey to co-ordinate the conference.
He met former vice president of Afghanistan, Marshal Abdul Rashid Dostum, and Turkish officials.
Mr Price said Washington and Ankara “agreed on an Afghan-led, Afghan-owned gathering supported by high-level attendance by the international community”.
He did not specify a date for the Istanbul meeting but said it would be “in the coming days".
Turkey has been helping the Biden administration in bridging the differences between the Afghan parties.
Turkish Foreign Minister Mevlut Cavusoglu this week met Afghan President Ashraf Ghani in Tajikistan to discuss preparations for the conference.
The Taliban have not confirmed their attendance.
On Thursday, US Secretary of Defence Lloyd Austin called Turkish Defence Minister Hulusi Akar and discussed Afghanistan.
“The secretary thanked Minister Akar for the significant role Turkey is playing as part of the Resolute Support Mission in Afghanistan, and in support of the ongoing peace process there," the Pentagon said.
"The two leaders also discussed the positive diplomatic developments and efforts to reduce all tension in the Eastern Mediterranean, where the secretary welcomed ongoing exploratory talks between Nato allies Turkey and Greece and the commitment of both governments to this process."
Iran is also holding talks with US officials and the US welcomed Tehran's engagement in helping with the peace process.
But a major challenge to negotiations are the continued attacks by the Taliban.
On Tuesday, the group fired two missiles at a coalition military base in Afghanistan's Khost province in the first attack on foreign troops there since the US withdrawal agreement was reached last year.