There are only a few consequential military powers today that can seriously attempt to fight a major war outside their own borders while simultaneously enduring opposition: US, Russia, China, Germany, France, UK. All the next tier powers down from that can be trivially crippled, locked down to their own territory and prevented from substantially joining the battle. IE there can be no WW3 until or unless the world changes a lot.
And I misspoke in saying "WWIII". What I meant was a nuclear exchange between the US, Russia and their allies. That's almost happened more times than most people realize. The Cuban Missile Crisis did pretty much happen in public. What would that have looked like on Twitter?
Sorry for off-topic, but is there anybody reading this who could help me claim a twitter username that is inactive for almost 10 years now? Any hints are welcome. AFAIK twitter doesn't do that officially anymore. It would be really awesome.