This internal NSA memo from SIGINT Director Teresa H Shea shows how the agency reacted to a October 2011 ruling of the FISA court, which was declassified after Edward Snowden’s revelations began. The ruling found that NSA had been intercepting the communications of non-targeted persons in the United States, violating the Fourth Amendment. The memo announces minimal changes to the Agency’s procedures, which the agency finally admitted were lacking in 2017, when it finally amended its mode of collection: see the Intercept article The Wiretap Rooms: The NSA’s Hidden Spy Hubs In Eight U.S. Cities, 25 June 2018.
This NSA email chain, asking an FBI contact to share the FISA justification for surveillance of a particular subject, makes it clear just how closely the two agencies cooperate: see the Intercept article NSA Secretly Helped Convict Defendants in U.S. Courts, 30 November 2017.
This undated NSA training presentation explains the use and function of PINWALE, the agency’s repository of FBI FISA data: see the Intercept article NSA Secretly Helped Convict Defendants in U.S. Courts, 30 November 2017.
This 2005 article from the NSA internal newsletter SIDToday makes it clear that, at that time, 40% of all the agency’s counterterrorism information was drawn from FISA sources, in collaboration with the FBI: see the Intercept article NSA Secretly Helped Convict Defendants in U.S. Courts, 30 November 2017.
This 18 April 2012 post from the NSA internal newsletter SSO Weekly reveals that AT&T (FAIRVIEW) cooperated with the NSA, under the terms of a FISA court order, to enable the agency to surveil the internet traffic going to and from the United Nations headquarters in New York: see the New York Times article AT&T Helped U.S. Spy on Internet on a Vast Scale, 15 August 2015.
This NSA Special Source Operations presentation from 22 March 2013 supplies a detail about the Breckenridge access point that supports the identification of the corporate partner codenamed STORMBREW as US telecommunications company Verizon: see the New York Times article AT&T Helped U.S. Spy on Internet on a Vast Scale, 15 August 2015.