Because Japan had exactly zero nukes to send back at the US. Russia has 2000. What percentage of them are you willing to gamble are working? Are 10% of them

Because Japan had exactly zero nukes to send back at the US. Russia has 2000. What percentage of them are you willing to gamble are working? Are 10% of them working? That's 200 US cities. So, no. We are absolutely not going to follow your logic. There is too much chance that they have enough nukes working to make us infinitely regret a nuclear exchange.