Donald Trump Calls For Biden To Resign Over Afghanistan Crisis (Video)
The rapid collapse of Afghanistan's government means American officials are increasingly concerned about the potential for a rise in terrorist threats against the US. The UK and the US are facing criticism over their handling of the deepening crisis in Afghanistan.
Donald Trump has called for Joe Biden to resign in the wake of the Taliban's takeover - describing the current situation as a "disgrace".
In a statement, the former president wrote: "What Joe Biden has done with Afghanistan is legendary. It will go down as one of the greatest defeats in American history!"
The end of America's "forever war".
Meanwhile, UK Foreign Secretary Dominic Raab has been accused of "going AWOL" after spending the past week on holiday abroad as the situation was unravelling.
Tom Tugendhat, a veteran and Conservative MP who now chairs the Commons Foreign Affairs Committee, told the BBC that he does not know how the Foreign, Commonwealth and Development Office will respond - adding this is "the biggest single policy disaster since Suez".
Government officials have said that Mr Raab is personally overseeing the Foreign Office's response, has engaged with international partners, and returned to the UK yesterday.
Prime Minister Boris Johnson has said that the Taliban should not be recognised as the government of Afghanistan, but added it was clear there will be a new administration in the country very soon.
PM: 'There is a change of regime happening'
He has also called for the West to adopt a "united position ... so that we do whatever we can to prevent Afghanistan lapsing back into being a breeding ground for terror".
Mr Johnson confirmed that Sir Laurie Bristow, the UK's ambassador to Afghanistan, has been "working around the clock" to evacuate British citizens - and has been at Kabul's airport to help process applications.
The prime minister added: "Our priority is to make sure that we deliver on our obligations to UK nationals in Afghanistan, to all those who helped the British effort in Afghanistan over 20 years, and to get them out as fast we can.
"We are going to get as many as we can out in the next few days."
The UN Security Council is going to meet later today.
Afghans try to flee at airport
Another 1,000 troops have been sent to Afghanistan to help evacuate US personnel and keep Kabul's airport secure - taking over air traffic control in the process.
However, the rapid collapse of the country's government means American officials are increasingly concerned about the potential for a rise in terrorist threats against the US.
Back in June, senior leaders at the Pentagon had said that an extremist group such as al Qaeda could regenerate in Afghanistan and pose a threat to the US homeland within two years.
Because of the evolving situation, they now believe that terrorist organisations may be able to grow much faster than expected.
US intelligence agencies are now working on a new timeline based on these developing threats.
All of this comes as officials push back against criticism of what has widely been seen as an intelligence failure - and the hurried evacuations out of Kabul have been likened to the 1975 fall of Saigon.
Last month, President Joe Biden said the prospects of the Taliban "overrunning everything and owning the whole country is highly unlikely" - something that the hardline Islamist group has now managed to achieve in just over a week.
One senior intelligence official told the AP news agency: "A rapid Taliban takeover was always a possibility … As the Taliban advanced, they ultimately met with little resistance. We have always been clear-eyed that this was possible, and tactical conditions on the ground can often evolve quickly."
Veterans have also expressed dismay at how quickly Afghanistan has fallen after 20 years of conflict, with more than 450 British personnel losing their lives during the war.
Jack Cummings, a former Royal Engineer, said: "Was it worth it, probably not. Did I lose my legs for nothing, looks like it. Did my mates die in vain, Yep."