Assistant to the Secretary of Defense for Public Affairs Jonathan Hoffman said at a Pentagon briefing on Friday that the US military was moving forward to reach the troop level of 8,600 in Afghanistan, reports Xinhua news agency.
"That is still going forward. We expect to meet that within the timeline laid out under the agreement with the Taliban," said Hoffman.
Also on Friday, US Special Representative for Afghan Reconciliation Zalmay Khalilzad confirmed to reporters that Washington was "in the phase of implementing the first phase of the agreement with regard to our condition-based withdrawal... gets us within 135 days of the signing of the agreement to 8,600".
These comments came after a series of deadly attacks in Afghanistan earlier this week, raising doubts about the US peace effort in this war-torn country.
"I will be travelling again soon to push for de-escalation, to push for reduction of violence, and to push for accelerating the release of prisoners," said Khalilzad in a conference call.
The special envoy also revealed that a new date to start intra-Afghan negotiations was under discussion, without providing further details.
An attack on a maternity hospital in the capital Kabul killed 24 civilians and injured 16 others on Tuesday, while a suicide bomb explosion targeting a funeral in eastern Nangarhar province killed 32 people and wounded 103 others.
The Taliban said they were not behind the twin attacks.
However, after the attacks, Afghan President Mohammad Ashraf Ghani ordered national security forces to end active defense position and resume offensives on militant groups including the Taliban.
The Taliban on Thursday claimed a truck bombing in Paktia province, which killed five civilians and injured 46 others, including several military personnel.
Violence still lingered in the war-torn country after the peace deal was signed between the US and the Taliban in Qatar on February 29, which paved the way for a phased American forces withdrawal.
The agreement faces challenges as the intra-Afghan dialogue that had been scheduled to begin on March 10 could not start due to differences over the release of 5,000 Taliban prisoners.