Western allies are trying to speed up the pace of their evacuations from Kabul, with just more than a week to go before the Taliban says it will stop allowing the operations that began when it conquered the capital on 15 August.
The US Defence Department said on Monday it would stick to its planned 31 August deadline to complete its evacuation operation in Afghanistan and withdraw all US troops from the airport in Kabul.
Pentagon spokesman John Kirby added that the US had seen the Taliban's public statements against an extension of the evacuation mission and was aware of the Islamist group's stated desires.
Taliban spokesperson Suhail Shaheen earlier told Britain's Sky News that 31 August was a "red line" for the group, which wants to regain its control of the country.
Kirby also dismissed repeated enquiries about how a possible extension could hypothetically play out. "We just aren't there yet," he said. "I am not going to speculate about post-August 31."
According to the Pentagon, about 5,800 US soldiers are currently deployed at the airport in Kabul to secure the evacuations.
As countries rush to evacuate citizens and local staff, many still hope to gain more time, an issue that is likely to dominate discussion among G7 leaders in a videoconference set for Tuesday.
British Prime Minister Boris Johnson hopes to persuade US President Joe Biden to give rescuers more time.
Biden agreed to pull US forces out of Afghanistan, as the US agreed to do under the Trump administration, but Western forces had expected to leave a Western-backed government in power. Instead, Taliban forces launched an offensive that saw them take almost all of Afghanistan in little more than a week, often with minor resistance.
Special EU meeting
Meanwhile Slovenia, the country holding the rotating presidency of the European Council, called for a special meeting to discuss the situation on Thursday.
Many of the Afghans who supported Western forces now fear reprisals from the militants.
The Taliban claims no such retribution is planned, but few believe the Islamists, leading to desperation at the airport as people seek to flee the country. Taliban members have also tried to push people back from the airport, sometimes violently.
The question now is how many people Western forces can airlift out of Kabul and how long they have to do it.
NATO on Monday refused to give a date for the end of its operations.
"The situation at Kabul airport remains extremely challenging and unpredictable," a NATO official said. Secretary General Jens Stoltenberg plans to participate in Tuesday's videoconference.
If the US sticks to the 31 August deadline, it would mean the evacuation operations would have to wrap up by the end of this week.
Multiple NATO members have spoken for an extension. Most have also said evacuation operations would be impossible without the US forces.
The pace of evacuation flights has practically doubled within the space of a day, according to NATO's representative in Afghanistan, Stefano Pontecorvo.
The US evacuated more than 10,400 people from Kabul between Sunday and Monday, the White House said, while international partners flew out a further 5,900.
Qatar is trying to mediate between the US and the Taliban to ensure people's safe passage from Afghanistan, according to Foreign Minister Sheikh Mohammed bin Abdulrahman Al Thani.
German Foreign Minister Heiko Maas thanked Al Thani for his leadership during a phone call, the ministry said in a tweet.
The airlift has, in turn, raised the question of where all the Afghans fleeing the country will eventually end up.
There were reports of some making it to Hungary and Jordan, saying it would be willing to let 2,500 transit through the country. But that still left many in places like Doha and Uzbekistan not sure where they would now call home.
But reports of violence are also strengthening their resolve to get out. For example, an Afghan security officer was killed when members of the Afghan security forces and soldiers from Germany and the US clashed with attackers at the north gate of Kabul airport.
Three Afghan personnel were injured in the incident at 6:43 am (local time) on Monday, the German army tweeted. They were treated by Norwegian paramedics at the airport compound.
It is not known who carried out the attack. On Sunday, the US government had expressed concern about a potential attack by the terrorist militia Islamic State at the airport or in the vicinity.
Seven Afghan civilians had died amid the chaos around the airport at the weekend, according to the British Ministry of Defence.
The Taliban is also focusing effort on taking control of the province of Panjshir, the only hold-out against the Islamists' rule.
Taliban fighters are gathering around the province even as the Taliban say they are seeking a political solution.