> There are no real consequences if you are backing off, and you can do it in any time.
That's not quite true. Sure, noone is going to start a war about such a withdrawal. However, nuclear arsenals are expensive to maintain and it's even more expensive to be in an arms race. Also, nobody wants to risk nuclear war if they can avoid it. Civilian populations will support disarmament in times where they don't feel directly threatened. That's why lot of leaders of all persuasions have advocated for and taken part in efforts to reduce their arsenals. Same goes for relations between countries generally and the huge economic benefits that come with trade and cooperation. Withdrawing from nuclear treaties endangers all of these benefits and increases risk. A country would only choose this route out of desperation or for likely immediate gain.
I think it really depends.
E.g. from the Western perspective, only US, UK, France, Russia and China have signed the treaty from nuclear countries.
India or Pakistan are not part of the treaties and for some reason, we don't see big problems.
There is only China left who might leave the treaty in the first place, anymore.
And we are so dependent of the China, that there is no guarantee for consequences. Should we treat China then equally than India? What that means?
Also, leaving the treaty does not mean that countries start massively increasing their arsenal. There will be just a lack of inspections and information exchange.
That's not quite true. Sure, noone is going to start a war about such a withdrawal. However, nuclear arsenals are expensive to maintain and it's even more expensive to be in an arms race. Also, nobody wants to risk nuclear war if they can avoid it. Civilian populations will support disarmament in times where they don't feel directly threatened. That's why lot of leaders of all persuasions have advocated for and taken part in efforts to reduce their arsenals. Same goes for relations between countries generally and the huge economic benefits that come with trade and cooperation. Withdrawing from nuclear treaties endangers all of these benefits and increases risk. A country would only choose this route out of desperation or for likely immediate gain.