While the basic plot is the same in the movie as in the book , there were significant changes . Noting these substantial changes , in the commentary track on the DVD release , Tom Clancy jokingly introduced himself as " the author of the book that he director Phil Alden Robinson , who is present with Clancy ignored . " Perhaps the largest change were the original terrorists . In the novel , they were Arab nationalists , but in the film , they were changed to neo-fascists . A common misconception is that this was done as a reaction to the September 11 , 2001 attacks , but the movie finished filming in June 2001
September 11 , 2001 attacks
September 11 attacks
The Sum of All Fears (film)