Russia has forces in Cuba and Venezuela right now, just not enough or with weaponry powerful enough to provoke the US.==
But if Russia and China for this matter will start arming and training them and push them to fight with US for Texas or Florida for example? What you will say then?
But it is a same thing what US is doing right now with Ukraine. At least Russia owed US a one for ww2 help but the score is cleared now because of this thing.
Ukraine is simply not big enough and does not have sufficient weaponry to attack Russia. It's difficult to conceive of any circumstance in which they would. And if Russia is so worried about an attack from Ukraine, perhaps they shouldn't have invaded.