There are better communications than in World Wars I and II.
It is hard to see what any combatant would gain from pushing the conflict outside of Ukraine/Russia.
Both Ukraine and Russia have been careful, so far, to refrain from pushing the conflict outside Ukraine and the border of Russia with Ukraine.
China sees an example of how attempting to regain territory, long independent, can spiral into severe, unwanted, consequences.
It is the opposite of how Hitler did not get any push-back after gobbling up several states.
In this case, the push-back from Ukraine was surprising, and surprisingly effective.
“It is hard to see what any combatant would gain from pushing the conflict outside of Ukraine/Russia.”
This isn’t about combatants. This is about the elites who run the world’s politics. They want you dead. You are a resource hog in their world.