Taliban official Abdul Salam Hanafi, speaking on the sidelines of a meeting in Moscow between prominent Afghan figures and Taliban representatives, said officials promised the pullout will begin this month.
"The Americans told us that from the beginning of February to the end of April, half of the troops from Afghanistan will be withdrawn," Hanafi said.
However, Pentagon spokesman Army Col. Rob Manning said American defense officials had not received orders to start withdrawing.
"Peace talks with the Taliban continue, but (the Defense Department) has not received a directive to change the force structure in Afghanistan," Manning said.
Hanafi said both the U.S. and the Taliban would create technical committees that "will work on a timetable for the withdrawal of remaining troops."
Pentagon officials say they have no orders to withdraw troops. But in anticipation of such an order in the future, given the Trump administration's achievement of what it calls a "framework" for potential peace negotiations between the Taliban and the Afghan government, military planners have been considering plans for how a pullout might be conducted.
The two-day talks in the Russian capital that wrapped up Wednesday sidelined the government of Afghanistan's President Ashraf Ghani.
Afghanistan's former president, Hamid Karzai, was involved in the meeting and hailed the discussions, saying the participants shared a desire for peace and stability and opposition to foreign intervention.
"We are happy with the outcome of the meeting," Karzai said.
Speaking after the Moscow meeting, the head of the Taliban delegation, Sher Mohammad Abbas Stanikzai, said talks on the U.S. withdrawal were continuing.
"We are in negotiations with the American side and we are trying that the American forces should go out as soon as possible," Stanikzai said. "The timeline is not fixed so far, it is not agreed upon, but we are negotiating this."
Efforts to find a negotiated end to Afghanistan's longest war have accelerated since the September appointment of Zalmay Khalilzad as Washington's peace envoy. He has held several meetings with the Taliban.
Talks have mostly focused on a U.S. troop withdrawal and guarantees from the Taliban that Afghanistan would not again be used as a safe haven for terrorists to attack other countries, according to both Khalilzad and Taliban officials.
In his State of the Union address on Tuesday, President Donald Trump said the U.S. has been holding constructive talks with a number of Afghan groups, including the Taliban.
"As we make progress in these negotiations, we will be able to reduce our troop presence and focus on counter-terrorism," he said.