Russia and China have helpd Iran develop these for the last ten years, basicaly under the guise of satelite launch vehicles. What you really want to worry about is Irans Shahab-6 IRSL-X-4 with a 5,632-6,200 kilometers range and a 1,000 750-500 kilogram warhead capacity. Pretty nifty really, based on Koreas Taep'o-dong 2.

And people think countrys like Russia and China dont support Iran, haha.

Ballistic missiles are at best a deterrent device. I have no problem with countries owning these. Chances are they would never be fired, unless the country is fired upon first.

As for other countries getting involved in the development, well, thats just plain economics. Whatever makes money.
Considering the US is helping develop the latest nuclear arms for Taiwan, I don't think the US is in any position to say anything about this.

As for them being non-operational, it just means they aren't deployed, but can be should they need to be.

The US has many operational nuclear missiles, which means they are on standby to be fired. All it takes is a target and ignition sequences. The warheads are already loaded onboard, and the missiles are fueled and ready for launch.

Iran seems to want them in case of the worst case scenario. Which would be knowlege that someone has just launched a ballistic weapon at them... in which case they would have time to arm their missiles with whatever they have, and launch before the enemys missiles hit home.