The United States, and many other world powers, but mostly the U.S., demands that other countries abandon their nuclear ambitions. Everyone can point out that the U.S. is a hypocrit because they have loads of nuclear weapons. When it comes down to it, the other nations want nuclear weapons to protect themselves from the world powers who already have their nukes. So they'll disarm if the powers disarm. But the powers won't disarm because then they become vulnerable to nations that don't disarm.

Simply put, no matter what happens, we're all screwed over. The safest answer would be for everyone to completely disarm, but that's unrealistic. Another unrealistic alternative is to let everyone have their missiles. By naming countries who can and can't have nuclear weapons people piss other people off. If everyone has the weapons, at least it puts everyone in a stalemate. "If you fire at us, we'll fire at you."

But since both of those options are unrealistic we are stuck in a world where the powers make the decisions. Let's face it, unless Iran does what the United States wants, there will be trouble, most likely military involvement. It's just how it's going to be. It doesn't mean it's right, but that's just the way it is. They say the winners write history, that doesn't only apply to after a war is over.