Lets, for a moment, presume Iran has Nuclear weapons - and uses them. Lets just remind that Israel is known to have at LEAST 90 nuclear warheads, and several of those missiles are likely prepped ready pointed at Iran.

To put it simply: That move DOES NOT end well. If anything, it ends strictly worse then simply accepting that Israel crippled Iran’s infrastructure. And any hope for normalization and opening trade up on the global market outside of China, Russia, and North Korea becomes basically zero until the regime is overthrown. Even worse - if Israel opts for nuclear strikes to follow up their conventional ones after being attacked with nuclear weapons,there is a good chance it’s not just several years of repair work, but decades of set back that could easily lead to mass scale discontentment and open revolt against the regime by several factions simultaneously.

The reality is: Israel is not a force capable of sustained occupation of an entity like Iran. But they are a force capable of a decapitating strike. And the entire reason is, Israel has VERY LIMITED force projection capabilities - and, because of a lack of land boarder with Iran, would need cooperation with other states that may not be thrilled with opening themselves up to direct conflict in the short to mid term. The only real reason Israel has room to do a strike is 1. It’s retaliatory, and 2. entities like Saudi Arabia are liable to be just fine with their regional rivals basically offing each other, as Saudi Arabia is in a MUCH better position to take advantage in the event of Iran’s regime collapsing.

Which brings us to: Just because you have nuclear weapons, does not mean you use them. The reality is, nuclear weapons are a weapon of last resort - unless you are France, and then it’s a nuclear warning shot… Because France is just different.