A wierd consequence of mutually assured destruction is that you need your adversary to be roughly on par with you. If one side gains a major advantage they may

A wierd consequence of mutually assured destruction is that you need your adversary to be roughly on par with you. If one side gains a major advantage they may decide to attack knowing that you'll have the worst of it. The weaker side may be more likely to use thier ultimate out of desperation and "nothing left to lose" type thinking. Further, the way to deal with anti-nuke defenses is to just send more nukes and/or lots of dummies too. Things like iron dome are 90% effective (reportedly, some think that number is too high and has a significant propaganda element)... You dont need a huge success rate for your nukes to be effective. Besides the consequences of a destroyed nuke are not great either, there's still a lot of uranium and plutonium getting dumped into the atmosphere. If your goal is to end nuclear proliferation, things that increase said proliferation are not ok.