We know Israel has nukes.
Israel will kill each and every person in Iran before they let Iran get nukes.

If Iran gets nukes, you will see a worldwide nuclear war within 50 or so years.

Also- yep neither China, USA, or Russia will ever use nukes unless a smaller country does.

China and Russia might dislike the US, but even they get that if this turns into a full blown nuke war, no one is gonna come out alive.

I don't think even Israel would use nukes. If they did, we, the US, wouldn't help them.