Snowden and Greenwald can't read. The FBI's Data Intercept Technology Unit is right there on the slides they released: https://i.imgur.com/setOJIm.jpg
This was well-known and commented on at the time Greenwald's articles were being published, with the NYT reporting on the program correctly the very next day by interviewing people actually involved in the program (verifying claims like real journalists — why didn't The Guardian think of that?).
https://www.cnet.com/news/no-evidence-of-nsas-direct-access-...
https://medium.com/@alecmuffett/how-to-talk-about-prism-and-...
https://medium.com/prism-truth/the-prism-details-matter-82a1...
In response, Greenwald doubled down on his incompetent misreading of the slides without providing any evidence to support his obviously ridiculous assertions.
https://www.theguardian.com/commentisfree/2013/jun/14/nsa-pa...