Russia and Iran have had a few bitter centuries and its doubtful they put their military in on their behalf and its unlikely Iran would want it. With that said, Russia would gladly supply them military aid if needed. Iran will suddenly have S-400's shooting down our planes.
China has investments with them, and would probably also give them aid.
Syria of course, but they are in no condition to help.
All that above would give any military a hard time. Its why the House of Saud and its Arab allies have not gone toe to toe with them, they know they will lose.
But this next list, will really blow up the region.
Hezbollah. They launch another attack on Israel. Sure they will lose, but it could inflame Arab terrorist groups to start making life miserable as well.
The Shite southern majority in Iraq. No sooner than we launch a war against Iran...we have to open another "front" in Iraq. The whole country could fall right back into chaos.
Then you have those who will sit this out and make sure we go at it alone. That would be Europe. They want to engage diplomatically, if we start shit, they'll bail on us.
Then the wild cards, Turkey and all the 'stan' countries. No one can say for certain what they'll do, other than whats in their best interest. And Iran has enough oil to make it in their best interest.
Then of course, nukes. We can't be for certain if they already created a few and are lying in some bunker we don't know about. Israel has the Samson initiative, should it look like they are going to lose at the hand of an enemy, they use them. Iran could just as easily have a few bombs to detonate if it feels the same way. We don't have to turn the country to glass, they will do it themselves if it means inflicting massive casualties on our forces there.
This is one fight we don't want to pick.
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