Can someone explain to me, someone that knows fudge all on the subject of modern war etc What is going to stop Putin from nuclear bombing countries when we keep on hitting them with heavier and heavier sanctions? I mean, he doesn’t strike me as someone who’s just going to sit there and take being backed into a corner….
Well, that's where the good old concept of "MAD" comes into play. (mutually assured destruction).
Putin (hopefully) well knows that that is one line he cannot cross first. The established doctrine in NATO is full and unrestricted retaliation with nuclear weapons towards Russia if such a line is breached. At least, if he has lost all sanity and no longer knows this, the people around him should still know...
The worrying parts (apart from the complete bonkers of the above concept) is the development of tactical battlefield nukes on one hand, and the enclave of Kaliningrad on the other.
As one develop heavier and heavier "conventional" weapons, such as the theremite-rocket-launcher Russia has, or other big guns, and smaller and smaller artillery-fired nukes, the border between them sort of fades. And that makes it really tough on "soft" western politicians who needs to respond to the use of such weapons.
Add in a few of the really big ones, and place them in Kaliningrad, from where they can strike at European capitals with minutes or no warning at all, it makes a feasible scenario where Putin can bite of as big a chunk of eastern Europe as he wants, before threatening with nukes from Kaliningrad. "Accept this end to the war, or I will nuke you."
There has been speculations that this was a plan, either for this war, or the next, however, I think now he has misjudged the response home and abroad, and that this may be the end of Putin. I would not be surprised if there either came to a palace coup, a public uprise or possibly a "heart attack" in a few days time. If so, I'd wager that history would show that the evil one tried to give an order to use nukes, but was restrained by the people around him.
As for what does brexit, nationalism, anti-globalism and other trends in our current time have to do with this, as certain other discussions goes here, neither are neccessarily the cause or to blame for what happens now, but it does not require very advanced "dot-to-dot"-drawing skills to see that certain movements acceptance of either blatant aid from Russia or russian associated companies, or more subverted aid, being intel, financial or other, has allowed them to be used by Russia for Russias gain. Some has done this in naive faith, other with a foul taste in their mouth, and others in full acceptance. History will not be nice to any of them at all! (of course, unless Russia wins and takes over the world. If so, History will not be nice, full stop)
Russia has supported and used these movements to create wedges between allies, cast doubts about treaties and obligations that previously was unshakable and unquestionable. That this has happened is beyond question.