Part of why i don't feel like russia will swing nukes anytime soon (unless burgers pour fire directly at russia or viceversa) is that there's no big red button and to fire a nuke you have to go through a shit ton of people and steps.
If one day Putin wakes up particulary angry and says "nuke kiveve NOW", he first has to go through his generals, who then have to go through a shit ton of more people, who then have to coordinate together and then have to actually get the nukes working over at a control base, who then have to all decide to push the button at the same time.
You bet your ass that wouldn't remain a secret for too long and the news would spread like wildfire, and since there has to be atleast a few people not wanting nuclear armaggedon inside the kremlin, some of them would refuse, putler can of course just mark em for death but this would just make everyone there realize "this guy is fucking crazy" and then silently put a bullet on his head.
This only applies in the hypotethical case that russia has not been attacked, nato has not stepped in directly, and it's just pudin wanting to launch a nuke because he can. Because if one of the previous events happens, then i bet the kremlin would be tempted into letting the nukes fly.