An increased military presence and security at checkpoints were visible in Kabul and a security source told Reuters the city had been placed on "high alert."
Under the Trump administration's February 2020 deal with the Taliban, foreign forces were to withdraw from the country by May 1 while the Taliban held off on attacking foreign troops and bases. But President Joe Biden announced last month, after reviewing the situation, that forces would stay in the country for months beyond May, withdrawing by Sept. 11.
Violence against Afghans has escalated starkly in recent weeks, with more than a hundred Afghan security force personnel killed.
On the eve of the previously agreed May 1 withdrawal deadline, a huge blast in eastern Logar killed dozens as they broke their fast during the holy Islamic month of Ramadan. It was not clear who was behind the attack.
The Taliban has responded to the Biden administration's decision with fiery rhetoric and threatened consequences, boycotting a crucial conference in Turkey scheduled for last month that had been planned to help jumpstart stalling Afghan peace talks in Doha.
Since then, contacts have been maintained, official and Taliban sources say, in an effort to try to get the Taliban back to negotiating table and agree to the extended foreign troop presence.
As of Saturday it was unclear whether concrete progress had been made and there had been no announcement on an extension.
Taliban spokesman Zabihullah Mujahid said on Twitter on Saturday that the passing deadline meant "this violation in principle has opened the way for (Taliban fighters) to take every counter-action it deems appropriate against the occupying forces." But he added that fighters were waiting on the decision of Taliban leadership.
Washington has also warned that if foreign forces were attacked while carrying out the withdrawal, they would defend themselves "with all the tools at our disposal."
Download the NBC News app for full coverage of the coronavirus outbreak
Experts said the Taliban threats should be taken seriously, but a number of factors meant that full-scale attacks against foreign targets could be averted, as the Taliban continued negotiations.
"We can't rule out attacks," said Michael Kugelman, deputy director of the Asia Programme at the Woodrow Wilson Center in Washington. "That said, the Taliban is less likely to attack foreign forces now that it knows there is a specific date when they will be leaving."
Also on Friday, the eve of the May 1 deadline, envoys from Russia, China, Pakistan and the United States held meetings with Taliban officials and Afghan government negotiators in the Qatari capital. The Taliban said they discussed the peace process and their request that Taliban leaders be removed from sanctions lists.