But how is it possible for this thing to be triggered automatically and at the same time, impossible to untrigger?

— Group Captain Lionel Mandrake, President Merkin Muffley, Dr. Strangelove (Peter Sellers)

8 seconds sound clip from the Dr. Strangelove movie soundboard.

You can hear this line at 00:52:00 in the Blu-ray version of the movie.

Quote context

[...]

- I commissioned last year a study of this project by the Bland Corporation.

- Based on the findings of the report, my conclusion was that this idea was not a practical deterrent for reasons which, at this moment, must be all too obvious.

- Then you mean it is possible for them to have built such a thing?

- Mr. President, the technology required is easily within the means of even the smallest nuclear power.

- It requires only the will to do so.

- But how is it possible for this thing to be triggered automatically and at the same time, impossible to untrigger?

- Mr. President, it is not only possible, it is essential.

- That is the whole idea of this machine, you know.

- Deterrence is the art of producing in the mind of the enemy the fear to attack.

- And so, because of the automated and irrevocable decision-making process which rules out human meddling, the Doomsday Machine is terrifying.

[...]