Clancy started working on the novel in 1979, setting the first chapter during the Yom Kippur War. Then he abandoned his idea for other novels until he wrote "The Cardinal of the Kremlin" (1988), where Ryan first meets Russian premier Narmonov. After figuring out the resolution to "The Sum of All Fears", Clancy then used his next novel "Clear and Present Danger" (1989) as a way to introduce future President Fowler. Speaking of the consistency, Clancy said: "The whole series really is a logical and connected network of plot lines which would continue to diverge and converge throughout the body of the work." The novel was notable for detailing the process in making a bomb; however, certain technical details were altered, and Clancy made clear in the novel's afterword that a lot of information in his book can be found in the public domain.