Former Joint Chiefs chairman says it happened during the Clinton administration . Shelton says a card giving the president access to nuclear launch instructions went missing . New instructions were quickly given to him , Shelton says . Once a month , Defense Department officials conduct an in-person verification to make sure the president has the right codes . Efforts to contact a Clinton spokesman were unsuccessful Thursday .
Former Joint Chiefs chairman says it happened during the Clinton administration . Shelton says a card giving the president access to nuclear launch instructions went missing . New instructions were quickly given to him , Shelton says . Efforts to contact a Clinton spokesman were unsuccessful Thursday .