I can only imagine how hard it must be to protect sources, but the end state must eventually be to provide evidence or there is no way to tell the difference between an intelligence service and a method for manufacturing unsubstantiated claims at the convenience of whoever operates the agency. Maybe I’m being naive.
No. By revealing a likely course of action, it can prevent them from taking that course of action.
For example, if I plan to cheat at a card game by keeping extra cards in my shirt sleeve and another player at the table says: "He cheats. I hear he keeps cards in his sleeves." Then it will much harder, perhaps impossible for me to cheat that way because everyone will be watching my sleeves and my movements carefully.
At some point presumably you have to provide evidence. If you never can, that’s when you sound like Alex Jones.
I don’t mean noop in the sense that nothing can happen as a result, so it was probably a bad choice of a word, but that it just doesn’t provide any info. Maybe you’re telling the truth, maybe you’re lying for your own reasons, I have no way to know and so what can I do with the info?
I see the point you’re making too, though, and it makes sense.
tl;dr: disclosing data could tell the adversary how we found out, leading to changes by the adversary or deaths of spies crucial to how we learned what we learned.