A limited exchange of nuclear weapons could kill a billion people in ensuing famines as the climate destabilises is the latest horror story about the greatest human mistake. Investing in racist murder. Genocide is the crime committed by any Government using nuclear weapons, and if so isolated would make themselves a target of every major nuclear power, but if retaliated against, would risk collapsing a house of cards sufficient to cause genocidal murder.
Therefore, any state that uses nuclear weapons is committing an international crime and makes itself a target. In the final analysis, the nuclear deterrent is a waste of money, a waste of energy, a waste of human effort.