There have always been those on both sides of the divide who enjoyed playing the nuclear card. If I remember correctly. Barry Goldwater made it part of his platform when he ran against JFK in 1964.
Fortunately cooler heads have always prevailed and, I would hope, will continue to do so.
Trump may be a buffoon but even a president will have checks and balances in place. He may be crazy enough to give Putin moral support "in principal" but he surely couldn't do more than that. Russia, after all, has been America's enemy since 1917.