In the Tannenwald reading he makes a claim that the use and even the existence of nuclear weapons has is taboo. Though these weapons are known to be in existence, it is not generally accepted into use by much of the world thus creating a sort of stigma about it. I gather from the reading that he is against nuclear weapons being put into use even as a deterrent. The simple fact that they are still considered an available weapon in arsenals is the primary reason that they have not been used since WWII. A situation of MAD is created with a semi-stable environment in which battles can be fought without much fear of the other side striking with a nuclear weapon. He also brings up that if deemed as illigal under international law, the nuclear weapons would be dismantled in all of the arsenals of the nuclear powers. I do not believe this to be the case. Due to the fact that it would be relatively easy for a state to secretly keep a few of their nuclear weapons, it would be impossible to totally relinquish the only real nuclear deterrent. "You bring a knife to a knife fight, but you still want your gun in case the other decides to pull out his".
Though these weapons are known and accepted as being different than conventional weapons due to their immense power, they should still always be ready to be used as a second-strike weapon, not a first strike weapon. However having the ability to keep them in the arsenal of available weapons gives the state a sense of protection against a first strike as well as an edge over the other state, who may not be a nuclear power by inciting fear in their troops, the government and the citizens of that state.