Boris Johnson has insisted the UK needs to “level” with the Taliban and make them understand the need to give safe passage to those wanting to leave Afghanistan.
The Prime Minister signalled further engagement between the West and the Taliban could be dependent on enabling the departures of Britons and Afghans left behind.
Mr Johnson also claimed it had been “clear for many months” that the situation in Afghanistan could change “very fast”, but insisted the UK Government’s response to the Taliban surge to power was not “spur of the moment”.
His remarks came during a visit to Merville Barracks in Colchester, Essex, to meet members of 16 Air Assault Brigade following their recent deployment to Afghanistan.
They helped evacuate British nationals and Afghans who worked alongside British forces as part of Operation Pitting, described by Mr Johnson as the “biggest-ever humanitarian airlift” in the UK’s history.
More than 8,000 former Afghan staff and their family members eligible under the Afghan relocations and assistance policy (Arap) were among the 15,000-plus people evacuated by the UK since August 13.
But thousands of Afghans who helped British efforts in the nation and their relatives, as well as other vulnerable civilians, are feared to have been left behind.
Mr Johnson told reporters: “The real job now is – two things we have got to do – we have got to make sure that we continue the work with local councils coming forward to help people find somewhere to live, make sure their kids have got somewhere to go to school, make sure they can be properly integrated into the UK economy and society.
“Secondly, we have got to make sure that we level with the Taliban or the new authorities in Kabul.
“They have got to understand that if they want engagement with the West, with us, our friends, and I know that they do, then the first priority for us is safe passage for those who want to leave.”
Earlier, Foreign Secretary Dominic Raab said evacuations may be able to resume from Kabul airport “in the near future” as he expressed a need for direct engagement with the Taliban.
The Cabinet minister raised hopes following talks in Qatar on Thursday.
Mr Raab said the UK will not recognise the Taliban in the “foreseeable future” but said there is an “important scope for engagement and dialogue”.
He was using a visit to the region to build a coalition with nearby nations to “exert the maximum moderating influence” on the Taliban as they “adjust to the new reality” of the group being in power.
The Foreign Secretary said he had “good conversations” with Qatari Emir Sheikh Tamim bin Hamad Al Thani about the “workability” of evacuations resuming from the airport for UK nationals and Afghans who worked with Britain.
Mr Johnson also faced questions about the UK’s response to the crisis after Defence Secretary Ben Wallace told the Spectator magazine he was arguing in July that “the game is up” and Britain should be accelerating efforts in Afghanistan as areas historically resistant to the Taliban fell.
Despite those apparent warnings, Mr Raab holidayed in Crete as Afghanistan was being recaptured by the Taliban.
On Wednesday, Mr Raab told MPs the “most likely” outcome foreseen by the Joint Intelligence Committee “and the military” after the withdrawal of foreign troops was “a steady deterioration from that point and it was unlikely Kabul would fall this year”.
However, he was also confronted with a “principal risk register” warning on July 22 that Afghanistan could fall to the Taliban much sooner than predicted.
Mr Johnson said Operation Pitting was “planned and prepared for months and months”, adding: “Long before the FCDO document to which you refer.
“To give you one example, the Baron Hotel – which was so important, the evacuation handling centre – was commissioned months ago and you can’t do an operation like this just on the spur of the moment.”
Pressed further, he added: “I think it’s been clear for many months that the situation could go very fast and that’s been part of the intelligence briefing.
“There have also been suggestions that the Afghan national defence force might hold on for longer. But logically you can see what happened.
“Once people felt in Afghanistan, once people in the Afghan army felt that they were no longer going to be getting that American air cover, then I think the logic for them became really to end their resistance and so things did go faster, but you can see to the extent of the planning that’s been put into Op Pitting.”
Mr Raab later confirmed Martin Longden will temporarily lead the UK’s new mission to Afghanistan in Doha, Qatar, adding on Twitter: “Martin has extensive experience in the region and led the @FCDOGovUK rapid deployment team at Kabul airport.”