‘Is it terrorists?” terrified teenager Robbie (Justin Chatwin) asks his dad Ray Ferrier (Tom Cruise) at the outset of the alien invasion that drives Steven Spielberg’s War of the Worlds—and you can understand his confusion. Characters find themselves covered in dust that comes from the ashes of vaporized bodies; survivors stumble past a wall plastered with flyers announcing missing family members; the whine of a jet engine announces destruction. Though ostensibly working from the 1898 H.G. Wells story that inspired a legendary radio broadcast and a previous 1953 film version, Spielberg sometimes seems to be making the first, risky attempt at September 11: The Motion Picture.

Yet he’s also making an old-fashioned disaster movie, the kind of “event” thriller that no other filmmaker has ever crafted with more rousing, crowd-pleasing skill. War of the Worlds sometimes finds the director working at the top of his game, and sometimes finds him struggling not to fall back on easy tricks while dealing with such heavy subtext. It’s the Spielberg of Schindler’s List arm-wrestling the Spielberg of Jurassic Park for control of the material, resulting in a film both nerve jangling and frustratingly generic.

WAR OF THE WORLDS ( * * * )
Directed by Steven Spielberg.
Starring Tom Cruise, Dakota Fanning, Tim Robbins.
(PG-13, 117 mins.) | At the Century Cinemas Del Monte Center, Northridge Cinemas,  Century Park Seven.

For most of the film’s first half, it’s squarely in the nerve-jangling category. There’s an eerie quiet to the early scenes of divorced dad Ray and his kids Robbie and Rachel (Dakota Fanning) finding their weekend together disrupted by freakish occurrences. Lightning strikes, electricity and cars fail, and soon massive mechanical tripods are rising from beneath the earth to fry unsuspecting onlookers. From the initial assault through the Ferriers’ grim quest for anywhere safe, War of the Worlds often works as well at being simply unsettling as it does at being big and momentous.

Then there’s the part where Spielberg realizes hundreds of millions of dollars are on the line. First there’s the presence of Tom Cruise, whose character is a divorced New Jersey dock worker. While Cruise is fine as a concerned parent, his movie-star presence is a constant reminder that this is a big blockbuster rather than the dark character piece it sometimes pretends to be. Screenwriters Josh Friedman and David Koepp turn Wells’ story into the same narrative that has driven disaster movies from Earthquake to The Day After Tomorrow: loved ones divided. It’s hard to work up genuine enthusiasm for the 50th variation on that theme.

Spielberg himself sometimes seems to be having the same problem. It’s not entirely fair to look at a movie this consistently tense and accuse him of phoning it in, but some of his choices here feel like the work of someone who opts for the familiar when he’s not sure what to do. That’s most evident during a sequence in which Cruise, Fanning and Robbins hide out silently from probing mechanical tentacles—a bit nearly identical to one in the last Spielberg/Cruise collaboration, Minority Report.

In the end, when this War of the Worlds finds the same weakness in the alien menace that Wells did over 100 years ago, little inconsistencies start to nag. They’re the kind of things that wouldn’t necessarily bother you in a fully enthralling movie, but here serve as reminders that there was a constant tug-of-war between serious post-9/11 allegory and happy-ending Hollywood spectacle.