What is a right, when it comes to nation states? There is only power. You only get to be a state if you have the power to make other people agree that you are one.
Anyone can demand, anyone can say “get stuffed.” What happens next depends on who has the power to achieve their goals. Power sometimes comes from moral justifiability, however. Other nations are less likely to oppose you if your certain actions are seen as moral by their population.
On the topic of nukes: Nuclear weapons are insanely powerful, much more so than the ones dropped in WW2. Their unrivaled potential to destroy and contaminate represent the most salient existential threat humanity and life in general has ever known. And sadly, their existence was essentially inevitable. But now that Pandora’s box has blown open, non-proliferation is a morally justifiable strategy. Think of how close we’ve come to nuclear war with only two rational actors involved. The more nuclear states there are, the more potential for their use, either on purpose, by accident, or by a third party who acquires them. Look at Venezuela. If they were nuclear, wouldn’t the impending state failure scare the shit out of you?
Non-proliferation is a UN treaty, not a US policy, but yes, as the most powerful economically and militarily, and therefore the state with arguably the most leverage internationally, not only is the US morally justified in leading an agenda of non-proliferation, it is morally obliged to do so for the sake of humanity. Sure it’s paternalistic, but Russia sure isn’t going to do it.
Of course, the “fair” thing to do is simultaneously push for mutual disarmament, which has been happening for many years. Every country that has the bomb, however, would find it very difficult to give up nuclear weapons altogether. This emphasizes the importance of non-proliferation.