Aslan says the following in The Magician's Nephew:
"It is not certain that some wicked one of your race will not find out a secret as evil as the Deplorable Word and use it to destroy all living things. And soon, very soon, before you are an old man and an old woman, great nations of your world will be ruled by tyrants who care no more for joy and justice and mercy than the Empress Jadis. Let your world beware. That is the warning."
The first line could imply that whatever secret hadn't been discovered yet, but it could also mean that it had been discovered, they just hadn't used it yet. Was Lewis thinking of a particular invention (e.g. nuclear weapons or other WMD), or was he thinking of a hypothetical future invention? If it was the former, is Lewis claiming that nuclear weapons and/or other WMD are intrinsically evil?
Also, was Lewis thinking of a specific tyrant (perhaps Josef Stalin)? Or does the fact that he uses plural (tyrants) indicate that he's thinking of several different tyrants?
Are these necessarily the same people (i.e. is the person who discovers/uses the equivalent of the deplorable word necessarily one of the tyrants)?