SSN is a techno-thriller novel, created by Tom Clancy and Martin H. Greenberg and published on December 1, 1996 as a tie-in to the video game of the same name. It follows the missions of USS Cheyenne, a United States Navy nuclear attack submarine, during a fictional war between the United States and China over the Spratly Islands. SSN is the second Clancy novel after Red Storm Rising (1986) that is not set in the Ryanverse.