Let’s also consider the stances of those countries on a nuclear first strike:
China: Unambiguous “No First Use”, with no exceptions
Iran: Doesn’t even have nukes and afaik has been cleared of ever trying to do so by international inspectors
Russia: Reserves the right to use nuclear weapons if WMD are deployed against itself or its allies or if the very existence of the state is threatened with conventional warfare
The US: Still has full first use.
For fun, the other countries with nukes:
The UK: Has openly stated they will use nukes in a pre-emptive strike, officially has no stance on a “No First Use” policy in order to “keep its enemies guessing”
Israel: Doesn’t have nukes (winkwinknudgenudge) but would 300% use them if they did
Let’s also consider the stances of those countries on a nuclear first strike:
For fun, the other countries with nukes: