"Sources and methods" seems to be an official NSA terminology to talk about the main categories things that whistleblowers were not supposed to whistleblow.
It came to Ciro Santilli's attention in the Reality film about Reality Winner, and are words she apparently used extensively and which are quoted e.g. at www.theguardian.com/us-news/2022/jul/25/reality-winner-leaked-file-on-russia-election-hacking-because-public-was-being-lied-to
Edward Snowden in 2013
. Source. From the film Prism, during interview with reporter Glenn Greenwald.Edward Snowden original interview cut by The Guardian (2013)
Source. 
Aptitude test scene from the Snowden 2016 film
. Source. FISA Court Order The Guardian discussion scene from the Snowden 2016 film
. Source. How is this Possible? scene from the Snowden 2016 film
. Source. Fresh Brains for You scene from the Snowden 2016 film
. Source. 
