Just six weeks after saying he thought a Taliban takeover was highly unlikely, Joe Biden conceded it happened faster than expected.

       In an address to the nation, the president said he stands by “squarely behind” his decision to withdraw troops from Afghanistan, but admitted that the collapse of the military and government happened much quicker than expected.

       “This did unfold more quickly than we anticipated,” the president said, noting that “the Afghan military collapsed, sometimes without trying to fight.”

       “Americans should not be fighting and dying in a war that the Afghan military is not willing to fight for itself,” he added.

       “How many more American lives is it worth? How many endless rows of headstones at Arlington National Cemetery?” the president asked.

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       “Mr Ghani insisted the Afghan forces would fight. Obviously, he was wrong,” Mr Biden said of President Ashraf Ghani’s promise to him at a meeting in June. Mr Ghani fled Afghanisation on Sunday.

       “If Afghanistan is unable to mount any real resistance to the Taliban now, there is no chance that in one more year, five more years or 20 more years, the US military boots on the ground would’ve made any difference.”

       He explained: “After 20 years I have learned the hard way that there is never a good time to withdraw.”

       “I’m now the fourth American president to preside over war in Afghanistan, two Democrats and two Republicans. I will not pass this responsibility onto a fifth President.”

       Mr Biden did not take questions after his speech in which he laid out the reasoning for why the US is leaving Afghanistan. He did not address much of the criticism over how the shambolic departure unfolded.

       The Department of Defense is working to restore a safe and secure environment so military and commercial flights can resume from Kabul’s airport which was a scene of chaos on Monday.

       The president warned the Taliban not to interfere with US evacuation from Afghanistan, threatening “devastating force, if necessary”.