Funny thing is, at least in the US, documents with different classification levels may contradict one another. I had a coworker who used to work on threat modeling code for USAF training sims, and as the story went, they would go to a classified-secret level meeting where the presenter would say that such-and-such surface-to-air missile had X capabilities, and then another classified-top-secret meeting later that day would list completely different capabilities. They would still have to write the training sim code according to the secret-level intel; I'm guessing this is so that if there was a leak, it wouldn't reveal that the DOD had the real info all along and risk either outing their sources or causing tech to be phased out more quickly, thus necessitating different countermeasures.

Some pretty wild trolling must have gone on back and forth between the US and the USSR towards the end of the Cold War.