At present it is to install and protect a pro-American government and destroy the Taliban to the extent possible. It is also to show the people that America is not there to destroy their culture or religion. It is a very complex attempt unlike any of our former wars.
Look I despise Islam and believe it to be the work of Satan but it cannot be attacked directly and destroyed without destroying hundreds of millions of people. Americans are not Nazis and won’t support such a thing. I support those things which can actually lead to the destruction or reform of Islam not self-aggrandizing phony preachers’ stunts.
You might as well try to install Santa Claus or The Easter Bunny.