Having won a narrow Electoral College victory in spite of a 7 million vote loss in the popular vote, Trump was in the mood for a victory lap. He withdrew all of the troops from Afghanistan over the objections of the military. The Afghan Army predictably collapsed within a few days.
When the generals told him that a Taliban parade in Kabul would make him look like a loser, he ordered air strikes. They were a complete failure. The situation was too far gone by that time, and there was no Afghan Army left to assist. Civilian casualties were heavy, however.
The evacuation was a fiasco. Trump blamed Obama and Bush, of course. The rest of the GOP fell into line and praised his courage for standing up to the Blob—even Tom Cotton and, inevitably, Lindsey Graham. His poll numbers did not budge.