Defence Secretary Ben Wallace has warned it is “arrogant” to think the UK could unilaterally prevent Afghanistan falling back into the grip of the Taliban.
With the militants closing in on the capital, Kabul, it was reported that arrangements were being made to airlift out the British ambassador Sir Laurie Bristow by Monday evening.
The Foreign, Commonwealth, and Development Office (FCDO) had intended Sir Laurie and a small team of officials to remain at the airport with other international diplomats.
However, The Sunday Telegraph reported that their departure had been brought forward amid fears the airport could be overrun as the Taliban continue their lightning advance through the country. The FCDO declined to comment.
Six hundred British troops are being deployed to the city to assist with the evacuation of the remaining nationals, as well as Afghans who worked with UK forces and who face reprisals if they fall into the hands of the Taliban.
With signs time is rapidly running out, a RAF Hercules was reported to have flown out of the airport on Saturday carrying diplomats and civilians.
The growing chaos – with the signs the government of President Ashraf Ghani is close to collapse – has met with anger and frustration among MPs and British military veterans who served in the country.
The situation was prompted by the decision of the Biden administration to withdraw all the remaining US troops from the country by the 20th anniversary next month of the 9/11 terror attacks.
The UK Government has faced accusations that it was abandoning the country to its fate after it – along with other international allies announced that it was following suit.
But writing in The Sunday Telegraph, Mr Wallace rejected claims that it represented “a failure of leadership and a betrayal of Afghanistan”.
He said that when the US announced its plan he had tried, without success to find other allies who would take their place and without them, the UK could not “go it alone”.
“A unilateral force would very quickly be viewed as an occupying force and, no matter how powerful the country that sends it, history shows us what happens to them in Afghanistan,” he said.
“It would be arrogant to think we could solve Afghanistan unilaterally. The solution can only come if the force is multinational and the nations involved bring to bear all the tools of nation building – hard power, soft power, foreign aid, and political alliances.
“And from the outset we need to be realistic that you have to manage these types of problems for decades, not fix them overnight.”
He said the position had been made more difficult by a deal which “wrongly suggested to the Taliban that they had won”.
His comments came as Mazar-e-Sharif in the north of the country became the latest city to fall to the the seemingly unstoppable advance of the militants.
Two powerful former warlords who had pledged to defend it were reported to have fled as the pro-government forces collapsed.
Meanwhile President Joe Biden announced that he was increasing the number of US troops being deployed to the country to help with the withdrawal of American nationals to 5,000.
At the same he strongly defended his decision to withdraw US forces despite the collapse of the Afghan army in the face of the Taliban advance.
He said that he when he entered office he had had a choice to go ahead with a deal struck by his predecessor Donald Trump to withdraw or to “ramp up” the US presence and deploy more combat troops.
“One more year, or five more years, of US military presence would not have made a difference if the Afghan military cannot or will not hold its own country,” he said in a statement.
“I was the fourth president to preside over an American troop presence in Afghanistan — two Republicans, two Democrats. I would not, and will not, pass this war onto a fifth.”