Can anyone recall a short story in which a new invention is developed which makes nuclear war (possibly all war) impossible?
At first everyone is delighted until the central character points out(to the President?) that conflict will continue in other forms – plots and assassinations and gives him a book to guide him in the new normal.
He last sentence names the book. It is “The works of Niccolo Machiavelli, the master of treachery and deceit.”