Frederick Kagan predictably seizes on the news of rapid Taliban advances in Afghanistan to argue that U.S. forces should have stayed longer and in larger numbers:

Adopting a more judicious approach would have required Mr. Biden to accept two things in addition to a longer timeline: the temporary deployment of additional U.S. forces and the slightly increased risk of American casualties.

If Biden had done things Kagan's way, it would have guaranteed more American casualties and the inevitable demands for escalation that would follow. What Kagan describes as a "responsible" withdrawal would have irresponsibly exposed American forces to renewed attacks on the off chance that keeping them there a little longer would have somehow prevented the wholesale collapse of the Afghan government's forces later on. If the only thing that U.S. troops were doing there was delaying the inevitable, keeping them there until next year wouldn't change anything.