I don't think any of these skirmishes have ever come close to an existential threat to either party. If things ever come to that, I have little doubt that nukes

I don't think any of these skirmishes have ever come close to an existential threat to either party. If things ever come to that, I have little doubt that nukes would be used. Principles, treaties, and ideals tend to go out the window when parties are backed in a corner with no alternative options.