In the critical hours of the 1973 Yom Kippur War, an Israeli fighter-bomber takes off carrying a single atomic bomb, only to be shot down by an Arab missile battery. Forward to the present day, and an ailing Russian president dies suddenly and is replaced by a man of an unknown quantity but believed to be a hardliner. Historian and CIA employee Jack Ryan accompanies his boss William Cabot to oversee the disarmament process with the new President, Nemerov, but soon things start going awry with chemical warfare in Grozny, missing Russian nuclear scientists and an apparently secret construction of an atomic device in the Ukraine.
Firstly, anyone who has read Tom Clancy's novel of the same name will have a rough idea of the basic premise of the film. Having said that, the film deviates from the book in several ways, in some understandably so, in others rather less fortunately. The main thrust, that the US and Russia (or the Soviet Union in the original story) are almost fooled into destroying each other via the detonation of a nuclear device on the territory of the continental United States, remains intact, but the villains, heroes and other third parties are somewhat altered.
This is an uneven and frustrating film. Although Ben Affleck gets a lot of hard criticism, some of it no doubt unfair, it was always going to be hard for him to step into the shoes of Jack Ryan given Harrison Ford's legacy. The device of altering his status from family man and father (as in the book) to a young analyst bedding his girlfriend Dr Catherine Muller (which also ignores one aspect of Ryan's character, namely his Catholicism, although in the novel he and Cathy had already had conjugal relations before getting married) makes him appear less solid, at least in the first half of the film. Having said that, Affleck makes a decent fist of it, especially in the latter half of the film as a man under pressure. The villains (Alan Bates as Dressler, Colm Feore as Olson and a handful of other extremists, paid traitors and renegades) have very little space in which to develop their characters. Ciaran Hinds is good as the hard-eyed but pragmatic Nemerov, but even the excellent Morgan Freeman and James Cromwell seem to find it hard to make their mark on their characters of William Cabot and President Fowler: in Cromwell's case I was unsure of whether we were supposed to like him or not. Perhaps with a democratically elected politician that is the point? Liev Schreiber also looks a bit young to play the hardened field officer John Clark, although the actor himself does a good job within the framework of the film (Clark's junior partner Ding Chavez does not feature in this movie). The ever-versatile Michael Byrne is suitably saturnine as Grushkov.
On the other hand the film does pick up pace in the second half, especially after the detonation of the bomb. The violence is not overly graphic but the effects and some simple ideas, like muting the sound for a short while as Ryan recovers from a helicopter crash caused by the blast, do convey something of the feel one might expect. Something of the violence of modern warfare is also shown in the initial military strikes both sides inflict on each other. At the same time, the sheer difficulty of cramming a novel of over 800 pages into a two hour film becomes apparent as some scenes flash by: in one part I did not even realise that one character had been murdered by another (unless of course the TV channel had censored part of the scene).
In sum, not a bad film, but Clancy purists will probably be somewhat disappointed (often the fate of many film adaptations of novels). Perhaps with an extra hour, or even as an expensive TV series, more could have been made from the original, but it's not a stinker either.
For differences between the novel and the film, see the Wikipedia article.