Rohit Kachroo reports on what has happened to the refugees who have managed to flee
By Lewis Denison
The UK has "hours, not weeks" to evacuate Britons and local allies from Afghanistan, the defence secretary has said, with an August 31 deadline looming ever closer.
The Taliban's swift insurgency and recapture of Afghanistan has resulted in thousands ascending on the capital Kabul's airport in a bid to flee the country before Western forces complete their withdrawal.
But chaotic scenes outside the airport means "not everyone will get out" before the deadline, as Defence Secretary Ben Wallace has repeatedly warned.
Here we take a look at the key questions surrounding the evacuation from Taliban-led Afghanistan.
Why are Western forces leaving Afghanistan?
Many people have blamed the crisis in Afghanistan on former US president Donald Trump for signing a deal with the Taliban, in which he agreed to withdraw the remaining 12,000 American troops from country, as long as the Islamist group ensured peace in the country and did not allow terror groups to operate.
But President Joe Biden was also keen to end what he described as "America's longest war" and continued with the withdrawal when he took over from Trump.
When Mr Biden took office there were around 2,500 troops still in Afghanistan, which many say kept a Taliban insurgency at bay.
The president allowed the final troops to begin to leave in early July - it was this move which many say sparked the Taliban's lightening-quick takeover of Afghanistan.
The UK has said the withdrawal of US troops meant British forces were forced to follow suit because America had been providing more than 95% of manpower and equipment on the ground.
Mr Biden said the choice was "either following through on the agreement to withdraw our forces, or escalating the conflict and sending thousands more American troops back into combat in Afghanistan, lurching into the third decade of conflict."
When signing the peace deal with the Taliban, Mr Trump said "if bad things happen, we'll go back with a force like no-one's ever seen" - Mr Biden does not seem keen to keep the former president's promise.
In light of the Taliban's advance across Afghanistan, the UK and US agreed to return soldiers to the country in order to evacuate those who needed to escape.
Who came up with the August 31 deadline?
President Biden set August 31 as the deadline for withdrawing US forces after inheriting a May 1 deadline from the deal signed by Mr Trump.
Despite indicating he had no choice but to complete the withdrawal, the US president does not regret his decision.
In a national address held after the fall of the previous Afghan government, Mr Biden said he stands "squarely" behind the move to remove US troops and that America's role there "was never supposed to be nation-building".When announcing the new deadline on July 8, Mr Biden said: "How many more, how many more thousands of American daughters and sons are you willing to risk?"
He added: "I will not send another generation of Americans to war in Afghanistan, with no reasonable expectation of achieving a different outcome."
In comments likely to haunt Mr Biden's presidency, he told reporters that Afghanistan falling to the Taliban would not be an acceptable outcome, suggesting local forces could defend against the group.
“Do I trust the Taliban? No,” Mr Biden said. “But I trust the capacity of the Afghan military, who is better trained, better equipped and more competent in terms of conducting war.”
What has to happen by August 31?
The deadline set by President Biden is for the withdrawal of US troops, not necessarily to complete evacuation efforts, but that cannot go ahead without American forces.
When setting the deadline, Mr Biden said if he did not stick to it "the Taliban would have again begun to target our forces".
Part of the agreement, signed by Mr Trump, was that the Taliban would not attack US forces, so long as the government continued to withdraw its troops.
"Staying meant US troops taking casualties," Mr Biden said.
The US determination to remove all its forces means Western allies, including the UK, have no choice but to follow suit.
Defence Secretary Wallace said: "It's really important for people to understand the United States have over 6,000 people in Kabul airport and when they withdraw that will take away the framework... and we will have to go as well."
The UK has admitted the final days before the deadline will be used to remove all military staff and equipment, which means civilians evacuations will end a number of days before August 31.
In a nutshell, the August 31 deadline for the US withdrawing its troops is a deadline for all Western forces to evacuate their citizens and allies.
For the UK, it means evacuating all British military, embassy staff, citizens, and Afghans who have worked with the UK in the past, such as interpreters.
Defence Secretary Wallace said security checks must be carried out on every Afghan, even if they worked with the UK, because its possible they may sympathise with the Taliban.
How many people does the US and UK have to evacuate by that point?
Both the UK and US have thousands of people they intend to evacuate from Afghanistan before August 31.
Mr Wallace said he did not wish to speculate on the numbers of people the UK would evacuate, but it's a "significant number".
The Ministry of Defence confirmed nearly 8,500 people have been evacuated from Afghanistan by the UK since August 13, as of Tuesday morning.
The MoD said on Twitter: "8,458 people have been evacuated by the UK since 13 August. 5,171 of those people are Afghan Relocation and Assistance Policy claimants.
"Nine UK military flights have left Kabul in the last 24 hours."
Armed forces minister James Heappey said "there are thousands more who we would like to get out if there is the time and the capacity."
America has so far evacuated more than 37,000 people from Afghanistan but it's thought there could be tens of thousands more still waiting to be rescued.
What if US extends the deadline - do the Taliban also need to agree to the deadline?
President Biden has left the door ajar for the possibility of extending the deadline, but he would rather he didn't have to.
In Sunday's update Mr Biden said “Our hope is that we don’t have to extend but there are discussions going on about how far we are.”
But the Taliban has threatened "consequences" if he does.
Taliban spokesperson Dr Suhail Shaheen told Sky News that August 31 is "a red line".
"President Biden announced that on 31 August they would withdraw all their military forces. So if they extend it that means they are extending occupation while there is no need for that." He added: "If the US or UK were to seek additional time to continue evacuations - the answer is no. Or there would be consequences."
No 10 said "discussions on the ground" had been held with the Taliban over extending the deadline evacuations, but officials were still working towards a deadline of the end of the month.
Asked about the comments, the Prime Minister’s official spokesman said: “I’ve seen the reports. I don’t think we’ve had any direct communication to that end.
“We will continue to run our evacuation process as long as the security situation allows.”