A few observations on Afghanistan:
* Trump agreed to a May pullout date; Biden backed it up to Sept 11/Aug 31.
The fighting season in the Afghan provinces always kicks off in Spring and ramps up in Summer. Very little fighting is done in the Winter months. Why wouldn't a US withdrawal be planned for the non-fighting season, instead of when the Taliban was ramping up its attacks and skirmishes? Military handover and evacuation would be much easier. Afghan Gov't would be under less pressure and have time to adjust to the US presence gone.
* One thing good about the remarkably fast Taliban takeover, very little fighting occurred, limiting killings and displacements. Not saying things can't turn ugly, but the takeover itself was relatively bloodless, compared to the expected 6-12 months of civil warfare the US envisioned.
* The US trained the Afghan army to fight a high-tech war against the Taliban guerrilla fighters. Drones, satellites, targeting, air power, "precision" guided weapons, etc. This requires a high level of training, coordination, discipline. But basics such as pay, supplies, logistics were either overlooked or left to corrupt Afghan officials. Once the US Air Force and support contractors left, the whole war strategy collapsed. Reportedly, contractors whisked away helicopter defense systems and their complicated military software, and Afghans were unprepared to repair damaged aircraft.
You'd think you'd want to train the Afghans in a sustainable form of warfare. And wouldn't take away crucial elements just as they were needed most.
* the Kabul airport during evacuation presented a very appealing target to any group opposed to the US presence. The last US troops plus tens of thousands of Afghanis who had cooperated with the US and its allies all huddled together in one chaotic crowd. Not sure what the options were, but leaving them outside the gates in desperation was a cruel mistake. They should have found some secure location within the airport walls and/or in the neighboring airport hotels where the people would be less exposed and vulnerable.
* working with the Taliban to some degree has become a necessity. They are in charge of the country and control Kabul with their weapons. After Sept 1, if you want to extract US contractors from the provinces or Afghan interpreters, the Taliban can permit or stop that. Also, both the Taliban and the US have an interest in containing ISIL and other terror groups. Not to mention trying to get humanitarian aid to people in desperate need. An trying to moderate/influence Taliban implementation of sharia and restrictions on women.
The reality is the Taliban is the gov't of Afghanistan and to accomplish much of anything in that country will require working with them.