This war will not be Israel and America against Iran but Israel and America against Russia, china, n Korea. The theater for this will be Iran. How do
you justify using nukes on a country to prevent them from pursuing nuclear independence?
N Korea doesn't care about Iran. I have been to S Korea and actually talked with a few North Koreans. They just want "occupied" South Korea back. They
don't even really like China either, but they are there closest ally. As for China and Russia, well maybe.
And no one is justifying the use of a nuclear option. Just that there is a "nuclear option".