Well it would basically draw us and the whole middle east into chaos.

Iran could attempt to mine or blockade / blow up anything in the Straits of Hormuz, which we would have to respond to with our Navy, Iran could blow up Saudi oil refineries with missiles or drones, Israel could do the same to Iran, Israel also has nuclear weapons…

Just might destroy the global economy if 20 to 25% of the world’s oil can no longer get to its destination. Might draw in the militaries of nations heavily reliant on said oil like India and China.