I don't think the Russians will do anything too crazy out of the blue but they do feel, not without some justification, that "regime change" and the isolation of Russia is the US goal for Russia.
You might remember Putin's angry denunciation of our intervention in Libya and the death of Qaddafi. He feels we have the same plans for him and he will fight if cornered. Russia is not very strong militarily in reality but he might role the dice in the belief that we are week.
Are you sober?