Churchill used these words in a short speech, entitled The Russian Enigma, that was broadcast by the BBC on 1 October 1939 – just under a month after the start of the Second World War. Speaking about the role that the Soviet Union (or Russia, as he had it) was likely to take in the war, he opened with the words "I cannot forecast to you the action of Russia. It is a riddle wrapped in a mystery inside an enigma ... "
You can read the speech in its entirety, on the website of the Churchill Society London.
© Haydn Thompson 2021