If there's any movie that might have been wise to shelve after Sept. 11, "The Sum of All Fears" is it. Of course, I can't tell you why without giving away a big part of the movie (which the TV commercials already give away). But suffice it to say if you're the least bit sensitive about terrorist explosions, steer well clear of this thing.

The movies that did get delayed in the wake of last year's attacks were either action-movie cartoonish ("Collateral Damage's" skyscraper bombing), tongue-in-cheek ("Big Trouble's" lax airport security and smuggled nuke) or unfortunate coincidences ("Sidewalks of New York" featured the twin towers prominently in several backgrounds).

This one portrays in all seriousness an enormously catastrophic terrorist attack, then virtually ignores its repercussions, casualties and aftermath except as they relate to a pseudo-intellectual political intrigue plot (substantially retailored from Tom Clancy's novel) about neo-Nazis trying to start World War III.

Beyond the post-attack poor taste, all director Phil Alden Robinson ("Sneakers," "Field of Dreams") has here is a run-of-the-mill Jack Ryan movie, rewritten to accommodate Ben Affleck as a younger hero than Harrison Ford was in "Patriot Games" and "Clear and Present Danger."

Affleck opens the movie as a young CIA historian version of Ryan, called into a meeting of high-ranking officials to brief them on a former Soviet general and nationalist hardliner (Ciaran Hinds) who has taken the reigns of power in Russia, causing a strain in US relations.

Meanwhile wealthy Euro-terrorist fascists (a now laughably P.C. substitute for the Arabs in the novel) have gotten their hands on a 30-year-old missing Israeli A-bomb and plan to blow up the Superbowl -- which despite the attendance of the president of the United States (an ineffectual James Cromwell), has taken virtually no security measures. The terrorists just drive a truck up to the stadium in the middle of the night to "make a delivery."

Through a complex and credibility-stretching set of circumstances, the baddies plan to frame the Ruskies for the blast, thus unbalancing world politics and apparently opening the door for a Nazi resurgence in some inadequately explained way. But thanks to a crash course in globetrotting cloak-and-dagger with the help of a CIA black ops spook (played with cryptic intelligence, wit and reserve by the great Liev Schreiber), Jack Ryan is on to them. The question is, will he have time to save the day?

Like other Clancy film adaptations, "Sum" has volumes of smart and fascinating details, both significant (the source of the bomb is determined by its plutonium signature) and trivial ("Get their shoes," Schreiber tells Affleck in order to take a pair of captured guards out of commission at a snowy Siberian army base).

But the movie's larger plot points are as witless as the minutia is clever. In a flashback, the missing bomb is on a fighter jet that gets shot down when the pilot leans down in the cockpit to pick up a picture of his wife and doesn't see a missile closing on him. Yeah, right.

The next scene is a tense quarrel in the White House situation room during what looks like a possible nuclear attack. Then in a contrived Hollywood reveal, it turns out to be a just a drill designed to sweat the audience a little -- as if the president, his national security advisor and the defense secretary would get into a blazing row when they're just play-acting.

The performances of Schreiber and Morgan Freeman (taking over for James Earl Jones as CIA honcho Bill Cabot) spackle over some of the movie's credibility gaps, and Affleck is adequate as Ryan -- no more or less charismatic than Harrison Ford. The younging-down of the main character is handled well, and his budding romance with his future wife (Bridget Moynahan, "Serendipity") is actually one of the movie's best assets and a source of some humor. When he tells her that he works for the CIA and can't make a dinner date because he's flying to Russia, she thinks he's lying and hangs up on him.

But while "The Sum of All Fears" resembles the two Harrison Ford movies enough to feel like a smooth continuation of the Jack Ryan saga in spite of its age-adjustment, and while it's enough unlike them that you don't miss Ford, it's just not the thinking person's spy thriller it pretends to be.

Then again, none of the series has ever quite measured up to "The Hunt for Red October" (the first Ryan movie starring Alec Baldwin and Sean Connery), so this picture could be seen as another step in the continuing oversimplification of Tom Clancy's dense novels.