What we know and what we don’t know about the fall crisis

The fall of 2022, the world came close to renewed nuclear use – at least that is what US government sources believed back then. “Fifty percent or even higher,” the Central Intelligence Agency assessed the possibility of nuclear use by Russia in Ukraine in October 2022. This remarkable uptick in the likelihood of nuclear weapons employment has yet to receive the scholarly attention it deserves. This introduction to the debate about the Fall Crisis sets the scene for what is known and what remains unknown about the events. It recalls the events and the popular literature that first reported them and rolls out the main puzzles. Was the “fifty percent” quote correct? Were Russian forces around Kherson really threatened with encirclement? What signal did the US intelligence community pick up? What role did US allies as well as India and China play?