Where would they have gotten the nucular (I like to spell it that way) fuel?
Maybe their nucular[sic] plants that they’ve had since the 70’s? The ROC doesn’t need to nuke Shanghai. It could drop a few bunker busters on the Three Gorges Dam.
They don't need actual "nuclear" weapons. They just need radioactive waste to make dirty bombs ( they have that from nuclear plants). Mix that with a quick drying epoxy, load it on cruise missiles, and explode them over Shanghai. It would make the city uninhabitable until it is all removed ( which would have to be done by hand with scrapers). That would take many many years, if they could do it at all.
With the break up of the Soviet Union there were opportunities. Plus, the Niger operation in Africa leaks like a sieve. Plus there was raw material missing from Qadafi’s stash. Finally, you have to ask, where does Iran get its uranium?