"Jarhead," set in 1991 during the first Gulf War, is a kind of lightweight variation on Stanley Kubrick's "Full Metal Jacket," with its evocation of the institution known as the United States Marine Corps, its love of the profane poetry of sergeants and the bond felt by young men locked in a common ordeal. But it's not quite a war movie because the author of the book on which it's based, Anthony Swofford, didn't quite fight in a war. (While he was willing, the Iraqi army was not. It had better things to do, such as running like hell.)

What is left is a portrait of Swofford and his band of gyrene brothers, wandering haplessly around what seems to be the world's biggest Christo project, looking for action while trying to overcome the soldier's truest enemy, ennui. Jake Gyllenhaal plays "Swoff," as he's called, and what's so good about the movie is Gyllenhaal's refusal to show off; he doesn't seem jealous of the camera's attention when it goes to others and is content, for long stretches, to serve simply as a prism though which other young men can be observed. Chief among these is his best buddy Troy, played by the superb actor Peter Sarsgaard. But there are others, and the movie has a nice ensemble sense to it. Jamie Foxx plays Sgt. Sykes, the small unit's lord and master. But he doesn't play it like a lord and master -- Foxx's Sykes will surprise you.

Once the shooting starts, director Sam Mendes fills his screen with surrealism. We end up in an ordeal that seems almost psychedelic -- vast vistas of destruction and the crispy husks of former human beings, which some will call pointless and others exactly to the point.

But "Jarhead" is far more an evocation than a judgment. The movie doesn't hate the corps or the war or the politicians who invented it. So it doesn't have the furious intensity of "Full Metal Jacket" or other screeds, even if it bears an anthropological resemblance.

-- Stephen Hunter