It depends on what you define as "a threat".
On a pure technical level, of course Russia is a threat. They have nuclear missiles, that can hit, and wipe out, most US cities. From that perspective, yeah they are a threat, without question.
However, on a practical level, if they launched nukes, we would to, and even though they would do more damage to us, than we did to them, that would only be because they have less to damage.
And that's the point. Should we be scared of Russia? More like a healthy respect would be a good policy. I'm still more concerned with states passing off nuclear weapons to non-state actors. Russia isn't going to do anything to start world war 3, unless we're stupid enough to force them into it. A healthy respect, will yield wisdom to not do that.