I was under the impression that Carl Sagan basically made up the concept of nuclear winter because of his political alignment.

And, yes, every country should have nuclear power and nuclear deterrence. Please contrast how the US negotiated with North Korea and Libya. Or what happened to Ukraine after they denuclearized. You might be impressed at how palatable peace becomes when leadership has to consider their personal safety and not just cynical economic and political calculus in their use of force.