Hi,
OK, thanks :) I haven't taken the time to read Snowden docs very carefully. So generally, I gather that NSA/CIA cooperates with friendly foreign agencies to establish intercepts.
Oh yes. The NSA has the Foreign Affairs Directorate (FAD) for that purpose or for the establishment and management of Foreign Partner Access (FPA) interception points/programms (for example RAMPART or WINDSTOP or SMARAGD), local Special US Liaison Activities (SUSLAs) like the one in Bad Aibling and Special US Liaison Offices (SUSLOs) for the communication.
And then they trade technology, data and results.
I think more or less. Besides the UKUSA 5-Eyes ring it is the question for foreign partner services in which ring they are and so how close the relationship is: 5Eyes, 9Eyes, 14Eyes (SIGINT Seniors Europe/SSEUR), SIGINT Seniors Pacific/SSPAC, 30Eyes or 41Eyes.
In part to circumvent laws preventing agencies from spying on citizens. Is that more or less accurate?
I would say yes. Intelligence rings are intelligence exchange rings and they are helping each other if laws preventing activities - one of the last examples was <https://theintercept.com/2016/08/14/nsa-gcsb-prism-surveillance-fullman-fiji/> - or the operator clicks the right box in his GUI to pretend that his action is compliant with the law ;) -- Katana