In "The sum of all fears" Clancy unrolls a terrifying scenario of palestinian terrorists exploding a nuclear bomb (actually, an almost-working H-bomb) on American soil. The book is pre 9/11 and I guess this storyline will sound even more convincing since the WTC distaster.
Clancy shows that it's not at all difficult to construct an atomic weapon. With some luck and good funding (that allows to obtain information and even foreign experts) a terrorist group can do it. In the book it's a hydrogen bomb, which is more complex than a simple nuclear one, so it can be even easier. Getting the bomb into the United States is trivial, if the terrorists are able to hold secrets.
The book also gives a good glimpse at the delicate balance of nuclear forced between USA and Russia. Even after the USSR came down and the cold war ended, is a provocation really enough to launch a worldwide nuclear holocaust ?
So far so good, but I have some serious reservations about this book. The main plot is interesting and original, but it's too damn hard to focus on, through all the line noise. In his latest works, Tom Clancy has just gotten too "wordly" - he just can't control his urge for irrelevant side stories. At 300 pages, this book would be excellent - but the 900+ page monster has just too much going on and it's difficult to filter all the chaff out for the real story.
For example, the initial "peace initiative" in the Middle East has little to do with anything (bar displaying Clancy's crazy, completely unrealistic idea). There's almost no connection made to it in the second part of the book, and it's irrelevant to the main plot. The same with the Japanese "temple logs", the same with the whole USS Maine story. When a "side story" is presented in the book, one would expect it to fit nicely in the plot. In Clancy's books, this is not always the case. Side stories are given for their own sake, and have a very minimal connection to the main plot. Sure, those stories are interesting, but it's difficult to wave off the feeling of their irrelevancy.