HH, if you repeat yourself, I will do so myself.
If you nuke pathetic Iran into the stone age (which won't happen, even the most aggressive plans will call only for a small number of tactical warheads), expect at least some of these to happen:
Russia will stay the recently adopted course of showing muscle, meaning more military, more bullying, more nuclear testing. America can bomb the world and it's OK? They are just as capable. And they are delighted that the megapiles of missles aren't useless anymore. And say hello to new president Putin!
Other countries, who had at best half-assed nuclear programs will actively and aggressively pursue to join the club.
The nuclear power Pakistan will hardly be happy if you plant mushrooms in their direct neighborhood. Even the most optimistic outlook will be massive radicalization.
The EU will be furious, confused, undecided and hopelessly at odds with itself. The possibilities are enormous here and each one is a step back from unity and peace.
You leaders will enforce a NAU at all costs as soon as possible to have access to more soldier material. After all, the US EMPIRE is in for some crazy infantry wars.
China will probably get Taiwan from the newly refreshed chickenhawks. While in history China wasn't very fond of outside wars (you could almost say, they were the most peaceful superpower ever) this will never continue in a world of aspiring hawks. The awakening Dragon will lick blood and he will like it.
Prepare to hear about the SCO (Shanghai Cooperation Organization) in the future.
Moderate muslim countries will have a hard time to stop the loons and ayatollahs taking over. Turkey, Egypt, Syria, Indonesia...the list is long.
Surprise:there are winners, though. The international war (and oil) machine will get so fat like never, ever before. Hooray.