Source: The New York Times - Link
Biden administration officials consistently believed they had the luxury of time. Military commanders overestimated the will of the Afghan forces to fight for their own country and underestimated how much the American withdrawal would destroy their confidence. The administration put too much faith in President Ashraf Ghani of Afghanistan, who fled Kabul as it fell.
And although Biden White House officials say that they held more than 50 meetings on embassy security and evacuations, and that so far no Americans have died in the operation, all the planning failed to prevent the mayhem when the Taliban took over Kabul in a matter of days.
Only in recent weeks did the administration change course from its original plan. By then it was too late.
This tragedy was years in the making. It is possible, however, that those years were able to breed enough resistance to the type of rule the Taliban are likely to impose. This will take years to play out.