US Defence Secretary Lloyd Austin said on Saturday that Afghan security forces must make sure they can slow the Taliban's momentum before attempting to retake territory.
This comes as Afghan armed forces seek to consolidate strategically important parts of the country.
Reuters reported that Afghanistan's military is overhauling its strategy against Taliban insurgents to focus on the most critical areas, including the capital Kabul and other cities, border crossings and vital infrastructure.
“They are consolidating their forces around the key population centres,” Mr Austin told reporters, during a visit to US state Alaska.
“In terms of whether or not it will stop the Taliban, I think the first thing to do is to make sure that they can slow the momentum.”
The US military is pulling out of Afghanistan and is set to end its mission there by August 31, on orders from President Joe Biden.
Mr Austin said he believed the Afghans had the capability and the capacity to make progress, but added that “we'll see what happens".
The politically perilous strategy appears to be a military necessity as overstretched Afghan troops try to prevent the loss of provincial capitals, which could deeply fracture the country.
Taliban insurgents are gaining control of more and more territory, which the Pentagon estimated on Wednesday now extends to over half of Afghanistan's district centres.
They are also putting pressure on the outskirts of half of the provincial capitals, trying to isolate them.
The Taliban's swift territorial gains are rattling Afghans just as the US withdraws from a war that succeeded in punishing Al Qaeda following its September 11, 2001, attacks on New York and Washington but failed to deliver peace for Afghanistan.
The US has continued to carry out air strikes to support Afghan government forces.
Mr Biden has promised financial assistance to Afghan forces and to redouble diplomatic efforts to revive stalled peace talks.
On Friday, he authorised up to $100 million from an emergency fund to meet “unexpected urgent” refugee needs stemming from the situation in Afghanistan, including for Afghan special immigration visa applicants.