I have heard that if you criticize the US military in your film then they won’t let you borrow tanks and other resources for it. If your film glorifies the US military then they will happily give you tons of resources for your movie, up to and including piles of money.

This is not outright government censorship - you can still make a picture that says “the US military sucks” - but it certainly has an effect on big-budget films that want every dollar they can get.