"The madmen who will start WW3 do not have your logic, mate."
Yes they do, it's why we don't, and won't, see hot wars directly involving nuclear powers. Conventional war would be too costly in terms of lost assets & personnel, and it'd spiral into nuclear standoff.
Conflicts involving proxies are about as close as it gets these days.
As you're seeing in the Middle East now, the US just parks a few carrier groups in the area in a defensive capacity and ensures Israel's security. Remember Iran's attack back in April that fizzled to nothing? Due to US, Jordanian & Saudi intervention (as well as Israeli of course), shooting down all of the incoming missiles & drones. No one is putting boots on the ground in Iran, it's not escalating to that point.
