[Tallguy]

How many nuclear weapons does the US need to be safe? If the US is afraid of 10 nuclear weapons in Iranian hands, is China afraid of 5000 in US hands?

It's not the technology that we need to fear. It's more the form of government of the nuclear-armed opponent. Democratic-Republics are pretty stable & predictable. Dictatorships are unpredictable in the extreme. So to answer your question: I'd be far more worried about North Korea, Pakistan or (hypothetically) Iran than I would Great Britain, France or India.

[Sawdring]

But as a deterrent, does 5000 nuclear weapons deter a Chines nuclear attack against the US or its allies?