"no two first-world, nuclear armed nations can ever engage eachother ever again without _the threat of_ total mutual nuclear annihilation occuring" certainly tw

"no two first-world, nuclear armed nations can ever engage eachother ever again without _the threat of_ total mutual nuclear annihilation occuring" certainly two nuclear nations can go to war without using nukes, either using direct limited confrontation (imagine Falklands war with Argentina having nukes) or through proxy (US vs Soviet Union or Russia many times)