According to the envoy, 135 days have passed since the agreement was signed and now the sides have reached a "key milestone" in its implementation.
"The U.S. has worked hard to carry out the 1st phase of its commitments under the Agreement, including to reduce forces & depart five bases. NATO troops have come down in proportional numbers," Khalilzad said on Twitter.

A US official who wished to remain anonymous told Tolo news broadcaster that the bases were located in Helmand, Uruzgan, Paktika and Laghman provinces.

Khalilzad also condemned the latest Taliban attack near the National Directorate of Security office in Samangan province that killed at least 10 people and injured dozens of others.

The Taliban were in power in Afghanistan from 1996-2001 before being overthrown by forces of a UN-mandated coalition of US-led international troops. The radical movement has since fought to regain recognition and expel foreign troops, including by waging an insurgency against the Afghan government and terrorizing the country's civilian population.

The Taliban have committed to reducing violence as part of a peace pact negotiated by the United States in the Qatari capital of Doha on February 29. In addition to a mutual release of prisoners and the launch of intra-Afghan talks, this was expected to pave the way for ending the almost two-decade long confrontation between Kabul and the radical group.