Jeffrey Goldberg unpacks the mind of Bibi here. Money quote:
Mr. Netanyahu doesn’t believe that Iran would necessarily launch a nuclear-tipped missile at Tel Aviv. He argues instead that Iran could bring about the eventual end of Israel simply by possessing such weaponry. “Iran’s militant proxies would be able to fire rockets and engage in other terror activities while enjoying a nuclear umbrella,” he said. This could lead to the depopulation of the Negev and the Galilee, both of which have already endured sustained rocket attacks by Hamas and Hezbollah.