Russia is struggling on a geo-political level. It has no access to a warm water port anymore, and it's access to the Black Sea can be cut off at any moment by Turkey (NATO). Defensively, it's northern borders are secure because the ocean is frozen most of the year, it's eastern border only a madman would invade from as you would have to go through all of Siberia to get anywhere. To the south it's borders are protected by mountain ranges. So Russias weak point is it's western border, hence they built up a big buffer zone with the Eastern European states - this buffer being chipped away at by NATO. Putin is worried that NATO are going to be camped on his doorstep, and he's trying to rebuild his buffer zone. Ukraine is his first, and "easiest" target. He feels it's a legitimate campaign due to the history between Russia and Ukraine, which extends back centuries. If the Russian population believe his rhetoric, then they'll be behind him (with state run TV pumping out his point of view 24/7, what else are they going to believe), but it'll be the younger generation that will hopefully see through his bullshit as they have wider access to news sources (although Putin is censoring Facebook, Twitter etc).
Is Putin crazy enough to launch nukes - who knows? The worrying thing is that the nuclear arsenal he now possesses is far more scary than most people think. For the last ten years, the Russians have given up on matching the US in the arms race due to the success of the US air defence systems. They have instead been working on new ICBMs that are supersonic, and therefore can elude the air defence - we're talking about missiles that can travel in excess of 3000kph - that's scary

but you think that's the worst weapon in his arsenal? Nope....they've also developed unmanned, nuclear powered torpedoes that carry a warhead up to 100Megatons....Hiroshima was a 15Kiloton bomb. These torpedoes go about silently in enemy waters, almost untraceable as there's no diesal engine and no manpower on board. If Putin decides to hit the button, we're all ****ed - so let's hope that some common sense prevails here and he gets removed from power ASAP