FVEY PSYOP (previously dismissed as tinfoilhattery when reported in places like The Guardian[1] or elsewhere over the years) has been revealed in The Incercept's reporting on Snowden documents[2].
As for legality, the important parts of Smith-Mundt were repealed several years ago. But you should totally trust them, PSYOP would never be carried out on their own populations, in social media or media in general.
As for legality, the important parts of Smith-Mundt were repealed several years ago. But you should totally trust them, PSYOP would never be carried out on their own populations, in social media or media in general.
http://www2.gwu.edu/~nsarchiv/NSAEBB/NSAEBB177/ is a good read, for those interested.
As is a history on Smith-Mundt: http://mountainrunner.us/2012/02/history_of_smith-mundt/
[1] http://www.theguardian.com/technology/2011/mar/17/us-spy-ope...
[2] https://firstlook.org/theintercept/2014/02/24/jtrig-manipula...