In the eyes of defense budgeting committees, Googling "Uranium" makes you a nuclear threat. In real terms, we don't know what a nuclear threat is, really, and that's the way American intelligence seems to want to keep it.

Hypothetically, let's say the United States or China or anyone else has a kind of missile defense system that can prevent any nuclear strike from coming within a hundred miles of its target or even further, even against the most advanced and chaotic by design missiles we know of. It would absolutely not be in the interest for the owner of such a defense system to let the opposition know such a defense system exists.

Let's pretend we have this defense system here in the United States. There's currently no reason to believe that the United States and China are going to be sending nuclear warheads at each other anytime soon, but both countries want to be ready to do it tomorrow if the issue comes up, so both countries want to be prepared to adequately deal with any potential resistance. If we keep this defense system a secret, China thinks they're set and ready to fly their nuclear weapons to California no problem. Then, hypothetically, when they do this defense system prevents them from landing and the United States would probably issue a counter strike without suffering any local casualties.

But if China did know about this imaginary defense system, their plans would involve it and everything they could know about it, and the same would go if the reverse were true. This means that keeping even the degree of a country's safety a secret is more valuable than the peace of mind of a people within that country.

Keeping that in mind, what the United States would consider a nuclear threat is only known to the people who won't be saying anything regarding to the matter. Depending on how you look at it you can feel free to find it comforting or terrifying.