Member-only story
It is perhaps not widely remembered that verbal agreements between JFK and Nikita Khrushchev of the USSR in 1962, the most recent time when the world may have come closest to nuclear Armageddon, called for the USSR to remove recently installed missiles from Cuba in exchange for an agreement on the part of the USA not to invade Cuba and to remove previously installed missiles from Turkey.
There was nothing in writing and, like the terse instructions in the fantasy show, MISSION IMPOSSIBLE, should any hard evidence be required, both parties (Soviet and American) were likely to disavow such.
And the tape (if there were such) would self-destruct.
The consequence of any nuclear exchange (and it is almost certain to be bilateral and fairly symmetric) are catastrophic and can be appreciated in part by a brief audiovisual summary.
Princeton has come up with a slightly over 4’ simulation.
You can watch it (Plan A) here:
Estimated casualties: 91.5M.
And that is early on and may be optimistic.
In the 1950s the USA offered NATO countries nuclear protection.
3 countries accepted the offer: Britain, Italy and Turkey.