Crazy Ivan is a cold war term used in the US to describe two different concepts. The most common usage was the name given to a maneuver used by Soviet submarines to clear their baffles to see if they were being followed. The second use was a catch-all term for the possibility of a rogue Soviet leader committing to military action, typically in reference to a limited launch of ICBMs against the US. The term Red October was sometimes used to describe the second concept, a reference to the 1984 Tom Clancy novel The Hunt for Red October in which a rogue Soviet submarine commander appears to threaten to launch a nuclear strike on the US. Coincidentally, the novel uses the first version of the term as a plot point.