"Sum Of All Fears" is Tom Clancy at the pinnacle of his writing career.
In this book he brings together the political manoeuvering of "Cardinal ...", the action of "Red Storm ..." and the tension of "... Red October" in one book.
As usual, this one starts with a bang, then slowly builds again until around the page 600 mark, at which point things really get going. The tension towards the climax is breath-taking. I still find the book gripping after several reads.
While inevitably abridged and rewritten for the film starring Ben Affleck, most of the important elements were retained. Missing though was the Marvin Russell sub-plot and the Arab terrorists were downplayed in favour of Neo-Nazis. I strongly recommend anyone who enjoyed the film to try the original book.
What amazes me is that Clancy can write something as brilliant as this, or the equally excellent "Executive Orders", but then bring out the at-best average "Red Rabbit". I can only conclude that he has either lost interest, or lost his inspiration for good writing. He doesn't need the money (there can be fewer more financially successful writers) and might be getting bored with writing, or at least the 'Ryanverse'.
So, try something else. Come up with a new character, or do as was done in "Without remorse" and "Rainbow Six" - take an 'also starring' character and create a story around them. The Robby Jackson character might be a good possibility, but I would be tempted to go for someone who is a barely mentioned one instead. That way, there is little to constrain the plot and scope.
But, please, no repeat of "Red Rabbit". I doubt Clancy's success could be sustained if another poor effort like that was published.