[dreig]

I was not saying that USSR is Russia.

In earlier comment you said: "Vietnam and Afghanistan .... Those were pure proxy wars. This is not a proxy war, it is a direct hot war." And here you wrote: "This is not a proxy war. Russia is involved directly on its border. A proxy war is in a far off land." And I was saying that Afghanistan was not a far off land, it was on the border, so your two usages of "proxy war" weren't consistent.

Sorry, I don't understand your second paragraph, I was not trying to draw an analogy with USSR and Afghanistan.

As I understand, your argument is instead that: "Afghanistan was not important to USSR, so USSR did not consider using nuclear weapons then", while "Ukraine is a core interest of Russia, so it will rather start a nuclear war (and risk destruction of the world) rather than back down and return to the positions before Feb 24th." I don't know if this statement is as obviously correct as it may seem to you. Certainly many believe that Russia is not willing to self-destruct to stand the ground here.