Well, if Putin is terminally ill there is a need of a few more levels of Russian military to be the same. To pull the button isn't just his own decision but first have to be decided at 2-3 levels before him.The Russian law tells nuclear weapons can only be used if the Russian states' existens is threttened, and that we know isn't by far the case at this stage. The only existens threttened is the Ukrainian by Putin and Russia.