by Chogy
Military Professionals
With the advent of nuclear weapons and secure delivery systems, there are certain nations that can simply never go down. They can be decimated, torched, suffer extremely, but massive populations and massive geography prohibit the invasion and occupation of these countries. I'd say China, Russia, and the U.S. fall into this category.
Consider: No two political systems hated each other more than NATO vs. the Warsaw Pact during the dark cold-war years. Proxy wars were fought, but none escalated because both sides knew that such a war would set civilization back 300 years, kill hundreds of millions, and no one would win.
The U.S. and China trade like crazy, which wasn't the case with U.S. and USSR, yet another reason not to war.
Again, no nation with advanced nuclear weapons is going to roll over and give up. The nukes will fly before that happens. And since we've never had a nuclear exchange, anything after that is pure speculation. Some very smart people pondered full-blown thermonuclear war for decades, and the conclusion was that there is no way to conduct it so there would be a clear "winner" and "loser."