Earlier quoted context omitted.
It would very much change the calculus for the UK and France, though. Maybe Israel, as well.
I'm not sure it'd change the calculus for the UK or France because they are NATO members which effectively ensures their second strike capability. (It certainly might change the cost/benefit calculation on building submarines, though!) Israel probably doesn't even subscribe to a second strike doctrine given that the potential adversaries they're trying to deter don't even have nuclear weapons.
If the Cold War had turned hot, the Soviet plan was to drive to the Rhine and then negotiate, on the theory that the US might sacrifice West Germany, but that France would definitely retaliate on its own.