An article about the history of US first strike plans
There was a lot of luck involved that we somehow survived the Cold War:
https://www.globalresearch.ca/u-s-military-planned-first-strike-nuclear-attack-on-every-city-in-russia-and-china-and-gave-many-low-level-field-commanders-the-power-to-push-the-button/5621871
https://www.democracynow.org/2017/12/6/doomsday_machine_daniel_ellsberg_reveals_he