Fighting has surged since the US began leaving last month, with the Taliban seizing swathes of territory.
All remaining US troops are expected to withdraw by an 11 September deadline.
On Tuesday, General Scott Miller said the country could face “very hard times” if its leadership is unable to unite once international troops leave.
The warning from the commander of the US-led mission in Afghanistan came just days after the UN warned of “dire scenarios” because the Taliban took hold of the many districts.
It said insurgents had taken quite 50 of 370 districts since May, encircling many cities and shutting in on the capital Kabul.
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“The security situation isn’t good immediately,” Gen Miller said during a rare press conference.
“Civil war is certainly a path which will be visualized if this continues on the trajectory it’s on immediately,” he added. “That should be a priority to the planet .”
He accused the Taliban of failing to scale back violence in line with an agreement it struck with the US.
The militant group claims to possess recently captured quite 100 districts across Afghanistan – something experts tie to the shortage folks air support to Afghan forces.
But Gen Miller didn’t rule out the US using airstrikes against the Taliban.
“What I [would] wish to see is not any airstrikes, but to urge to no airstrikes, you stop all violence,” he told reporters.
US-led forces ousted the Taliban from power in Afghanistan in October 2001. The group had been harboring Osama bin Laden and other al-Qaeda figures linked to the 9/11 attacks within the US.
President Biden has said the American pullout is justified as US forces have made sure Afghanistan cannot again become a base for foreign jihadists to plot against the West.
Afghan President Ashraf Ghani insists the country’s security forces are fully capable of keeping insurgents cornered, but many believe the withdrawal risks casting Afghanistan back to the grip of the Taliban.
President Biden has pledged that the US will still support Afghanistan after pulling troops out, but not “militarily”.
The last German troops left Afghanistan on Tuesday, bringing to an end almost 20 years of involvement within the country.
Some 150,000 Germans have served there since 2001, the defense ministry said.
