Perhaps, depending on specific intent, credibility, and the nature of harm threatened.

But since this is about surveillance, I hope that detection of verbal threats is not a goal of government surveillance because it's difficult to imagine how that could be accomplished without significant loss of privacy or other liberties.

I don't think you're advocating to have our personal conversations continuously monitored whenever outside, but in the context of this thread, that's what it sounds like.

> then it is a criminal matter.

In very limited and clearly defined ways only: https://www.law.georgetown.edu/icap/wp-content/uploads/sites...

Pretty much everything is a crime if you do it while blacker or trashier than the local baseline.