It will cause WWIII.
But it will not last decades.
Iran will have and use nukes. Israel and the US will retaliate.
Pak will be involved somewhere along the line.
It will not last long.
Our nuke defense policy has been based on the fact that Russia is not run by suicidal maniacs.
We now will be forced to deal with suicidal maniacs and therefore our defense policy is not going to work.
Where do the ChiComs fit into this picture ?