SSN may refer to:
SSN (1996) is a novel created by Tom Clancy and Martin Greenberg following the missions of the U.S. Navy nuclear attack submarine USS Cheyenne (SSN-773) during a fictional war with China over the Spratly Islands, based on the video game of the same name.
A loosely connected collection of "scenario" chapters in support of the eponymous video game, the novel continues the Clancy tradition of large amounts of attention to detail, particularly regarding the description and use of various military equipment. It is, however, unique in one important way: true to the title, almost the entire book describes the operations of Cheyenne. Other Clancy books follow a more global path, featuring sub-plots, entire military operations, politics and personal sub-plots.
This is one of only three Clancy novels not falling into the Jack Ryan universe, the others being Red Storm Rising and Against All Enemies.
SSN (hull classification symbol)
An SSN is a nuclear-powered general-purpose attack submarine. SSN is the US Navy hull classification symbol for such vessels; the SS denotes a submarine and the N denotes nuclear power. The designation SSN is used not just in the United States Navy (USN), but throughout NATO under STANAG 1166.