Keep in mind that, whether or not the initial invasion of Afghanistan was justified, it immediately became a football in the US political game. George W. Bush was elected on a platform that included "no nation building", and he certainly didn't. (I have a personal theory that the invasion of Iraq was solely due to the fact that the war in Afghanistan as of 2002-3 was not going to get Bush re-elected. Bush also failed to include the costs of the Afghanistan and Iraq wars in his 2005 budget (https://www.nytimes.com/2004/02/03/us/president-s-budget-pro...).)

The war in Afghanistan was started badly, continued thoughtlessly, and, naturally, ended poorly. As it was originally destined to do.