By the way, my understanding is that it was never as simple as two countries colluding to share raw data with each other; there had to be essentially a "launder

By the way, my understanding is that it was never as simple as two countries colluding to share raw data with each other; there had to be essentially a "laundering" of the data by turning it into analyzed intelligence, so that an NSA analyst couldn't just explicitly task a selector on a US-resident AMCIT via another FVEY partner. If you think about it from the lawyers' perspective, it goes something like this: I(a)) A can gather data on BCITs. I(b)) A cannot gather data or cause data to be gathered on ACITs. II(a)) B can gather data on ACITs. II(b)) B cannot gather data or cause data to be gathered on BCITs. III) Data gathered via (I(a)) or (II(a)) is lawfully collected. IV) Lawfully-collected data may be turned into intelligence. V) A and B can share intelligence that is gathered by lawful means. Therefore, A can receive intelligence on ACITs and B can receive intelligence on BCITs, so long as they do not derive that intelligence by gathering data or causing data to be gathered on their own citizens. Now, this was pre-9/11; after that, who knows what gloves came off?