The announcement followed protracted negotiations in the Qatari capital Doha between the United States and the Taliban and a meeting between US Secretary of State Mike Pompeo, Defense Secretary Mark Esper and Afghan President Ashraf Ghani during the Munich Security Conference.

A deeper agreement paving the way for a major US troop withdrawal from Afghanistan could be a political boost for President Donald Trump, who has repeatedly promised to stop "endless wars" as he seeks re-election in November.

"It was violence that derailed the signing of the agreement in September. Now we have an agreement on the reduction of violence. And, should the Talibs implement what they've committed to doing, we will move forward with the agreement," the senior administration official told reporters in Munich.

He added that the agreement was very specific and covered all Afghan forces, saying the US military would be monitoring violence levels to verify whether or not the Taliban was honouring it.

"And our commitment, in terms of reduction of forces which is both conditions based and in phases is very much tied to delivery on the commitments that they have made, and will be," the official said.

There are about 13,000 US troops as well as thousands of other NATO personnel in Afghanistan, 18 years after a US-led coalition invaded the country following the September 11, 2001 al Qaeda attacks on the United States.

The United States is aiming to cut troop numbers to about 9000, a Western diplomat told Reuters earlier this week.

Doha has been the venue for talks between the warring sides since 2018 even as fighting has continued across the country, killing hundreds of civilians and soldiers as the Taliban have expanded their territorial control.

Last month the Special Inspector General for Afghanistan Reconstruction, a US government agency, assessed that there had been a record-high number of attacks by the Taliban and other anti-government forces in the last three months of 2019.

Australian Associated Press