AFFLECK, ROBINSON ADD NEW LIFE TO JACK RYAN SERIES.

Byline: Glenn Whipp Film Critic

While squirming in your seat during the grimmest of grim moments in the expertly crafted political potboiler ``The Sum of All Fears,'' it's hard to avoid thinking of Russell Crowe's ``Gladiator'' warrior bellowing, ``Are we not entertained?'' while he's wading through the carnage.

Are we not entertained? Well, yes and no. Yes, in the sense that thrillers don't come much better than ``The Sum of All Fears'' these days.

The movie deftly reinvents the Tom Clancy series, turning back the clock on Jack Ryan by a good 30 years, and, managing in the process, to transform the reluctant spy into an approximation of a flesh-and-blood summer movie character.

The thing is, ``The Sum of All Fears'' does such a good job in depicting its massive, horrific act of terrorism that it puts its audience in something of a bind. ``Sum'' is smart for a popcorn spy flick, but the source material is a Clancy novel, and no matter how intelligently screenwriters Paul Attanasio and Daniel Pyne ply their trade, there's no getting around the fact that this is fiction at its pulpiest. Everything is predicated on one man, Jack Ryan, saving the world.

So for that kind of movie, the film's jarring depiction of terrorism hits a little too close to home. For all the hand wringing over trifles like ``Collateral Damage'' and ``Big Trouble,'' there was little in those movies that was truly upsetting. Be warned: The devastatingly brutal horror in ``The Sum of All Fears'' is shocking because it feels real. When it happens, it's a pin-drop moment.

Perhaps the film's biggest surprise is how effortlessly Ben Affleck moves into the role of Ryan, a character previously played by Alec Baldwin and, most recently and famously, by Harrison Ford. Affleck's previous attempts at action heroes have resulted in a parade of callow young men; here, he gets it right, confidently taking Ryan through his paces as a smart (and yes, ladies, sensitive) desk jockey who morphs into an action hero.

``Sum'' changes Clancy's terrorists from Arabs to neo-Nazis, who believe (and it's not such a stretch as it's presented here) that they can use terrorism to gain world domination. As Dressler (Alan Bates), the fuhrer- in-waiting, puts it: ``Hitler wasn't crazy; he was stupid. You don't fight Russia and America. You get Russia and America to fight each other and destroy themselves.''

Dressler's goal is to use terrorist acts to fuel fear and loathing in the superpowers. As the body count mounts, Ryan and his CIA mentor (Morgan Freeman) try to ferret out the truth. And, in a nod to women in the audience, Ryan must also deal with his fledgling feelings for a pretty doctor (Bridget Moynahan), who's a little surprised by her boyfriend's ever-increasing role in world events.

Director Phil Alden Robinson (``Field of Dreams,'' ``Sneakers'') proves to be an inspired choice for the material, probing the story's political repercussions with an incisive intelligence and staging the action with a captivating ability to surprise. If the movie becomes predictable in its final act, it isn't so much the filmmakers' failings as it is a certain need for the movie to adhere to the audience's expectations for easy answers and instant justice.

The movie gets a lot of mileage from its supporting cast, all uniformly excellent. When James Cromwell's embattled president bickers with his advisers - Philip Baker Hall, Ron Rifkin, Bruce McGill, among others - as the world spins out of control, the heated confrontations have the authentic feel of desperate men grasping at straws. It's another disturbing note of realism in a summer movie that might be a little too close to the headlines for its own good.

THE SUM OF ALL FEARS - Three stars

(PG-13: violence, disaster images, brief strong language)

Starring: Ben Affleck, Morgan Freeman, James Cromwell.

Director: Phil Alden Robinson.

Running time: 2 hr. 4 min.

Playing: Wide release.