"What about the last stage in the plan?
The blowback after they proceed with this will be unfortunate for them.
Unless Russia and China are prepared to fund, back, and supply, not to mention provide troops,and confront the West going with plan A will only create a situation wherein Iran has to be completely obliterated. World War III would be a distinct possibility, but then again, we already in WWIV. Do Russia and China want to play? Maybe. That could be the plan.
Then, what choice do we have?
Russia and China will sit back hoping to pick up the pieces. All they have to do is give lip service to Iran, thereby emboldening them, and wait for the West to take them out. Russia and China's only interest in Iran is oil and they will not jeapordize that access, either before the shooting starts (by abandoning Iran), or after the shooting starts (by taking a bullet for Iran). All out war with the West would be easier (if necessary) following the showdown between Iran and the West, and any resulting wearing down of our forces or arms.