At any given time, and for the last 70 years, there have been any number of grave nuclear threats to the US, and some of them have been pretty darned immediate. That's why the members of the Congresstional Intelligence committees have security clearances. There's no need to declassify them all.
In many cases, the fact we know a threat exists automatically reveals how we know it...and leads them to hide it better.
That's "the rub" as I see it...
There's two different perspectives (and there's validity to both)
1) Certain things have to remain secret because if they were public knowledge, that would both a- tip off potential enemies we're on to them (as you made reference to), and b- would cause panics that would destabilize and make bad situation worse
vs.
2) US taxpayers are paying to fund the US military industrial complex, and have a right to know what they're paying for. Which, at a basic level, I can understand the Ron/Rand Paul way of thinking on that. As, the notion of "you keep giving us your money, we can't tell you what we're doing with it, just know that we have your best interests in mind" doesn't necessarily sit well with a lot of people (and I get that)
Walking that delicate tightrope has always been a challenge for military superpowers. Two things that people almost universally dislike is having to pay taxes to fund these kinds of endeavors... and being kept in the dark on the details.
Whistleblowing made the situation even more murky...as the same entities we're supposed to entrust with keeping us safe (even if they can't share the details) were exposed as having been spying on American citizens.
The "unfortunate reality" of this whole thing is that in order for an entity to have enough surveillance power to keep Americans safe, that comes with the ability of performing the kind of warrantless "snooping" on people that leaves a bad taste in a lot of peoples' mouths.
I heard an interview with a former SF operator (I forget the details of who was conducting the interview now, but I'm sure it'll keep me awake trying to think of it now that I'm mentioning it lol), but they called it "The Due Process Conundrum". What he was explaining was that you can't 100% due process & privacy and 100% security...and that it's more like assigning attribute points to a character in a video game "You've got these 100 points, you can allocate some to due process and privacy, and can allocate some to security...but they both can't be 100 simultaneously, they can only add up to 100"