The Afghan military was probably infiltrated by the Taliban for years and years

[bluewater]

3. Demographics and underdevelopment muddied any mission

The population of Afghanistan is around 37,466,414 as of 2021,[6] which includes the roughly 3 million Afghan citizens living as refugees in both Pakistan and Iran

Approximately 46% of the population is under 15 years of age, and 74% of all Afghans live in rural areas.[4] The average woman gives birth to five children during her entire life, the highest fertility rate outside of Africa. About 6.8% of all babies die in child-birth or infancy.[4] The average life expectancy of the nation was reported in 2019 at around 63 years

Afghanistan ranks 210th in GDP per capita at $2474, and that's the purchasing power parity number that takes into account local prices.

Afghanistan was just too big at 39 million people and too poor for "nation building" to work.