In response to your last statement, I found this Amazon review [1] (of all sources!) of Ellsberg's book fascinating.
It's written by an older gentleman who was apparently involved in Nuclear policy in the late 70s and early 80s.
Here is the relevant snippet:
> To a degree, my time on nuclear weapons was a decade later than Ellsberg, ironically my first day after my PhD was the day Ellsberg's material hit the NY Times. Coming from MIT, and Ellsberg then being at MIT, I was looked at a bit askance. Yet over the next decade as I became involved in the Comprehensive Test Ban Treaty, especially during the Carter period, it was clear that the only way to use a nuclear weapon was not to use a nuclear weapon.
> The RISOP [Red Integrated Strategic Offensive Plan, or the US Government's best counterplan, i.e. how the Soviets would retaliate] scenarios showed the annihilation of life on the planet. There was no way to win, first strike or otherwise. A Russian and US nuclear war was the destruction of all. Ironically in my later discussions with my Russian partners after the fall it was clear that they too understood this, positioning or not.
So, it seems like NPT [2] states understand that first strike (against one another) is a bankrupt strategy, since it results in MAD [3], if not a global extinction event.
A state might not ever externally disavow the first strike strategy for posturing reasons, but it is almost certainly not viewed as an effective winning strategy, internally.
[1]: https://www.amazon.com/gp/customer-reviews/R2SL7WCQW1R6KN/re...
[2]: https://en.wikipedia.org/wiki/Treaty_on_the_Non-Proliferatio... Notable non-signatories of the NPT include India, Israel, Pakistan, and DPRK.
[3]: https://en.wikipedia.org/wiki/Mutual_assured_destruction