You will see lot of interviews and blaming this administration for the chaos. I bet it will happen to any administration. Trump tried to negotiate with Taliban , now it seems his negation was a fair option. I do not think Taliban will keep their words and the negotiation did not work.
US has army and military all over the world why not in Afghanistan? Presence of 2500 US army/military were helping Afgan military.
They do not have balls to fight against Taliban and they may have good reason behind it ( will be targeted to their family and friends).