The US will remove all staff from its embassy in the Afghan capital Kabul in the next 72 hours, US TV network CNN reported on Sunday.
"A core group of top US officials will stay at the Kabul airport for now," CNN's national security correspondent Kylie Atwood tweeted.
The move comes after US President Joe Biden said he had authorised sending another 1,000 troops to the country to ensure the "orderly and safe drawdown" of forces, increasing the number of marines and soldiers sent to aid evacuation efforts to 3,000.
Mr Biden ordered US forces to withdraw from Afghanistan by August 31, before the Taliban took over large parts of the country and major cities in a 10-day offensive.
On Sunday, the Taliban took over the key city of Jalalabad, closing off the last remaining border crossing out of Afghanistan.
Countries such as Canada, Germany and the UK have also been moving to withdraw their diplomats as the situation worsens, with the Taliban surrounding Kabul on Sunday afternoon.
Negotiations inside the Presidential Palace indicate that President Ashraf Ghani may plan to hand power over to a transitional government.
The Taliban said they would not take over the capital by force and would instead await the "peaceful transition" of power.
After that announcement, acting Interior Minister Abdul Mirzakwal said in a video message that the capital would remain unscathed and secured.
He also said there would be a transitional government. Until then, Afghan forces have been instructed to maintain law and order, he said.
Government departments asked employees to go home and private businesses and banks have closed for the day.
The Taliban told government workers they would be safe.