On Thermonuclear War is a book by Herman Kahn, a military strategist at the RAND Corporation, although it was written only a year before he left RAND to form the Hudson Institute. It is a controversial treatise on the nature and theory of war in the thermonuclear age. In it, Kahn calmly discusses the strategic doctrines of nuclear war and its effect on the international balance of power. Widely read on both sides of the Iron curtain, it is noteworthy for its views on the lack of credibility of a purely thermonuclear deterrent and how a country could "win" a nuclear war. Kahn introduced the Doomsday Machine as a rhetorical device to show the limits of John von Neumann's strategy of Mutually assured destruction or MAD. The book helped popularize the term megadeath, which Kahn coined in 1953. Kahn's stated purpose in writing the book was "avoiding disaster and buying time, without specifying the use of this time." The title of the book is inspired by the classic volume On War, by Carl von Clausewitz.
Of the book, Hubert H. Humphrey said: "New thoughts, particularly those which contradict current assumptions, are always painful for the human mind to contemplate. On Thermonuclear War is filled with such thoughts."
First published in 1960 by the Princeton University Press (ISBN 0-313-20060-2), it was republished as a paperback by Transaction Publishers in 2007 (ISBN 978-1-4128-0064-0).