i know a lot of westerners have this sort of "nato v the world" perception of things, or "nato v russia" or "the free world v communism". most living people today were warped by the blockbuster films of the 70s and 80s into at least having that global order presented as background; it's the null hypothesis, that we all struggle against.

when you're talking about signals intelligence, that's not a helpful way to see the world. it will lead you astray.

rather, what you have is a sort of inner circle within nato that is composed of the old british empire and is connected via the "ukusa agreement", signed in 1941. these are  the "five eyes" - canada, the united states, the united kingdom, australia & new zealand. this network also has outposts in india & the former british african colonies. the five eyes (+ india, south africa) does not share intelligence with the rest of nato, with japan, with israel (at least not officially), with the saudis or with any other nation that is adjunct to the western alliance.

nato intelligence sharing is a thing, surely. but, it happens at an outer layer and the germans, particularly, are often forced to act as competitors to the five eyes, to try to figure out what they're doing.

the reality is that the germans have been spying on us for decades, and we really never stopped spying on them at all. it always follows that, when these sorts of things come up, the germans are a prime suspect.

...even if they often fly under the radar.

(which is a technology they stole from us, remember)