It’s an animated documentary _ which is perhaps a contradiction in terms.

Israeli director Ari Folman thought the unusual technique was the only way to tell his story of recovering from long-repressed, nightmarish memories of his time as a young Israeli soldier waging war in 1980s Lebanon.

"Waltz with Bashir," competing for the top prize at the Cannes Film Festival, is based on interviews with Folman’s friends and fellow former soldiers, which were recorded and used as audio in the film. In a few cases, when his friends hoped to maintain their privacy, actors recounted their stories.

Folman, who has written for the HBO series "In Treatment," said Thursday that he saw no other alternative.

"Making it a plain documentary film, I mean, what would it look like?" he said. "You would see middle-aged men, 40-45 years old, giving interviews to the camera, telling stories that happened 20 years ago. And then what would you see on the screen? How would you film these nightmares on the screen?"

"It’s all about memory, it’s about lost memory, it’s about repression, it’s about `Where do our memories go when we repress them?’" Folman said. "Do they still live in us? Do they live outside of our body? It’s about dreams, it’s about hallucination. It’s about subconscious, it’s about all those things that the best thing is to draw them."

In the movie _ which has a deeply anti-war message _ Folman depicts young soldiers plowing through enemy territory on tanks, spraying gunfire in all directions without really knowing whom they are shooting at. Haunting images are backed by a rock soundtrack of ’80s music.

The film traces Folman’s attempts to recall the 1982 massacre in the Beirut camps of Sabra and Shatila by Israeli-backed Christian militiamen. Folman and other Israeli soldiers were posted nearby during the massacre.

At a news conference one reporter of Lebanese origin questioned why Folman didn’t focus more on Israeli liability. After the massacre, an Israeli commission of inquiry found that Ariel Sharon, then the defense minister, was indirectly responsible, and he was forced to resign.

Folman said he wanted to keep the film personal.

"It’s about memory," he said. "I didn’t have the urge to make any inquiry regarding who in the Israeli leadership or the leadership in the army knew that there was a massacre going on for three days. There was a federal inquiry for this thing. They did their job, 25 years ago."

In the film’s final minute, the animation gives way to real footage taken in the massacre’s aftermath. It’s an admission by the filmmaker that animation alone cannot convey the full horror of what happened.

"I just thought, really basically, that I don’t want you as the audience to go out of the theater after watching `Waltz with Bashir’ and think, `Yes, this is a cool animated film; yes, nice drawings, good music."

"In order to put the whole film in proportion, those 50 seconds were essential to me," he said.