I’m not going to get into details, but Embassy and/or Non-combatant evacuation plans are in place for pretty much every Embassy and diplomatic post. Sometimes, like Benghazi, they never get implemented because political, diplomatic, or military leaders ignore signals or get caught flat-footed. But they do exist.
It’s been a bread an butter mission of the military since the first diplomats went overseas. The Boxer Rebellion in China about 120 years ago being the biggest most involved of these missions.
I worked an Afghanistan evac plan about 7 years ago. Something we write as a standard matter of procedure. Part and parcel of these types of plans are a security force that goes in and takes over operations. Their focus is on gathering up the all the evacuees, U.S. and other allied diplomats, U.S. citizens, foreign nationals with a U.S. connection, allied citizens, etc. That force can be scoped in size from a few hundred to tens of thousands, based on the threats the force faces. The military knows how to execute this tactical task, and will likely do it very well.
But that is the easy part, the real issue is that Afghanistan is a utter strategic failure by the foreign policy establishment. Remember, this was the “Good War,” unlike the bad war in Iraq. Just one thing, no one, neither Mr Bush’s team nor Mr. Obama’s team ever clearly articulated just what success would look like. In Iraq we, after some fits and starts, established a functional state, corrupt as hell, misfires a lot, and too willing to overlook Iranian misdeeds, but it is functional. Afghanistan never got there, once we pulled out of an area, it collapsed back into tribal infighting once any pressure, either political or military, was applied. The diplomats and senior military leaders fooled themselves into thinking just a little more time would get them to turn the corner. But it never happened. We never could figure out how to turn the Afghan government and military into something that could stand on its own.
Mr. Trump took the least bad option he could find. Mr. Biden in his zeal to dump anything related to his predecessor found the most bad option and now soldiers and Marines will have to clean up the mess as best they can.