https://www.intelligence.senate.gov/sites/default/files/hearings/ciasuseofjournal00unit.pdf
https://www.archives.gov/files/research/jfk/releases/docid-32403785.pdf
Just scroll through them, skim, pretty much any part will be interesting. The upshot is that the free press and public message is controlled, especially on "dirty" subjects where government actors and rogue elements of government want their actions covered up.
What about foreign journalists?