Who could imagine any American president allowing murderous thugs to set the terms of our military’s surrender? But that’s what has been happening and it crystalized Tuesday.

The Taliban declared that no more Afghans should go to the Kabul airport, that those already there should leave and then they shut the main airport road. For all practical purposes, those words and actions ended the mercy mission of getting our ­allies out.

And Biden didn’t object. Not even a whimper, just silent ­acceptance.

Even more unforgivable, by agreeing to the Taliban’s demand that he stick to his own initial deadline of Aug. 31 for the withdrawal of all troops, Biden shows he is willing to strand thousands of Americans behind enemy lines.

Exactly how many Americans will be left behind is unknown, but most estimates put it in the thousands. They are now hos­tages to Biden’s fear and failure.

Their fate is uncertain, but the fate of the tens of thousands of abandoned Afghans who helped us and whom we promised to rescue is almost certain death.

This is extraordinarily callous and will ricochet around the world as evidence that America is no longer the home of the brave.

As is always the case with appeasement, our allies will be shaken and our adversaries emboldened.

The crisis at the airport has been building for more than a week, but Biden still had a chance to adapt by moving the deadline back so the evacuation could be completed.