Huddled in the dark in close proximity to their fellow men and women, cinema audiences experience vividly the claustrophobia of Das Boot or any of Hitchcock's single-location sizzlers (Lifeboat, Rope, Rear Window). Samuel Maoz's Lebanon, following in this tradition, gives spatial confinement a new intensity. Aside from the shots of sunflower fields that bookend the film, the action is restricted to the interior of
an Israeli tank that is grinding implacably into enemy territory. We see only what goes on inside that formidable tin can, along with whatever the characters can make out as they squint through the gunsight.

It is June 1982, the beginning of the first Lebanon war. A platoon is manoeuvring its tank into a town that has recently received a visit from the Israeli air force. It's really no more than a spot of house-cleaning, combing the area for anything that the bombs didn't flatten. Any obstacles can be removed with the squeeze of a trigger. That's the idea. But, as Clint Eastwood's Will Munny lamented in Unforgiven: "It's a hell of a thing, killing a man."

Maoz, who based the script on his own time as a gunner in Israel's tank corps, doesn't bother with a plot. The momentum of the vehicle and our dread of what it will find drives the film forward. Inside the hulking metal shell are four young men who are as soft as falafel. Shmulik (Yoav Donat) is the greenhorn who lowers himself into the tank with the trepidation of a man entering his own grave. The commanding officer, Assi (Itay Tiran), barely seems more experienced - he's just been frightened for longer. Hertzel (Oshri Cohen) is the loader. He'd be the swaggerer of the group, if only there were room to swagger. Even here, the driver Yigal (Michael Moshonov) stands out as the nervous type. He wants to get a message to his parents that he's safe. Had the poor lad seen any war movies, he would know that the surest way to place your life in danger is to tell Mum: "Stick the dinner on, I'll be home in a jiffy."

It is night when the tank starts moving, and the instructions are to head across a banana plantation. But peering at the nausea-green images as the tank lurches unpredictably through the countryside, you feel as though you are trapped behind the eyes of a rampaging ogre. Even Shmulik's gun isn't quite the asset it promises to be. The first few times he has to use it, his judgement is off. He leaves behind a tableau of flesh, blood and chicken feathers that, viewed through the gunsight, demonstrates Maoz's ability to bring nonchalance to the most gruesome spectacle. It has to be so: with the camera limited to showing only what the men can see, there is a necessary flatness to the horrors on screen. In that context, it's no wonder the military constructs a euphemistic vocabulary. Dead bodies are referred to as "angels". Phosphorus has been banned, but its use is permitted so long as it goes by the name of "exploding smoke".

That type of strangulated humour lingers about the corners of Maoz's script. When the film permits the men a few minutes of downtime, Assi recounts an amusing anecdote about being deflowered during a period of mourning. The monologue lets some fresh air into the picture, but it also feels psychologically correct in the way it bundles sex and death together. These are, after all, men who weep where they smoke, smoke where they sleep, sleep next to where they pee. The time for personal space has passed.

As the soldiers unravel, the close-ups of them become tighter, but also more abstract. The camera lends their sweat-and-oil-streaked faces the look of distressed saints in an El Greco altarpiece. In the men's perspective on the outside world, which doesn't exist except through the crosshairs of their bullet-pocked gunsight, Maoz has hit upon an unbeatable metaphor for the combat mentality. The film features no breathtaking landscapes or eye-popping action sequences, yet it would be impossible to deny that it is forcefully cinematic. The director has mapped out every inch of his crowded frame, every metallic groan and clang that assaults the ears, to deepen our sensory experience. He may keep us cooped up, but he stretches the fabric of film to its limits.