How U.S., Afghan governments failed to adequately train Afghan security forces after spending $90 billion over 20 years

The inability of Afghan forces to function independently in the months before the U.S. withdrawal from Afghanistan is the fault largely of the U.S. and Afghan governments, according to a new report. 

It was a mistake to train them to be "a mirror image of U.S. forces, which required a high degree of professional military sophistication and leadership," qualities that the Afghan forces did not have. The report, released Tuesday by the special inspector general for Afghanistan Reconstruction (SIGAR), points out that the Afghan air force, which was supposed to be "the greatest advantage the force had over the Taliban," wasn't even expected to be self-sufficient until 2030.

Over a period of 20 years, the U.S. invested nearly $90 billion in Afghan security assistance and trained and built up Afghan security forces to help them defend their country against the Taliban.