Audiences at the Berlin film festival are submitting themselves to a groundbreaking immersive multimedia project on nuclear war, whose risk its US filmmakers say has soared over the last year.

"The Bomb" by Kevin Ford, Smriti Keshari and investigative journalist Eric Schlosser ("Fast Food Nation") surrounds cinemagoers with floor-to-ceiling screens, with a live band playing the score.

The 360-degree installation uses the shock and horror that atomic weapons inspire to explore their history, destructive power and rampant proliferation today.

After stunning viewers at New York's Tribeca festival last year, the filmmakers brought the experience to Berlin, once on the front line of the Cold War and one of the likely first targets of a thermonuclear conflagration.

Running a little less than an hour, it bombards viewers with never-before-seen archival footage and recent images of missile launches and atomic explosions, as well as old television commercials touting the glories of nuclear energy.

The filmmakers say their message could not be more urgent, with nine nations possessing about 15,000 nuclear weapons -- 90 percent of them in the United States and Russia -- and global politics in a state of upheaval.

- 'Perverse appeal' -

Schlosser said the volatile personalities of some of the world's leaders with their "fingers on the button" haunted his sleep.

He said that while members of the US military involved in the nuclear weapons programme had to undergo a battery of tests insuring their reliability, the same did not apply to the US president.

"So I think it's safe to say that my current president (Donald Trump) would not be allowed in the Air Force or anywhere near a nuclear weapon," he said.

"And yet he, right now, he's the only person in the US authorised to order the use of a nuclear weapon."

Pedro Gething, a 31-year-old Portuguese man in the audience, called the project "interesting" but admitted it "kind of freaks me out".

"There was a lot I didn't know and visually, it was quite an experience, very beautiful," he said.

Eleonore Clemente, 26, from France, also admired the "aesthetics" of the installation -- underlining what the filmmakers call the "perverse appeal" that nuclear weapons can exert.

"Nuclear weapons are the most powerful machines" ever created, Keshari said.

"There is definitely something seductive about them. It is this seduction we wanted to get across."

She was drawn to the project after reading Schlosser's 2013 book "Command and Control: Nuclear Weapons, the Damascus Accident, and the Illusion of Safety".

The producers say that the two biggest threats to humankind are climate change and the atomic bomb.

But while the effects of global warming can be seen, for example, in a proliferation of catastrophic weather events, nuclear weapons remain out of sight and thus often out of mind.

"That may be a way of reaching more people," Eleonore said.

"Maybe it's strange to say 'I liked the film, I found it beautiful' because it's talking about awful things. But maybe a more 'specialist' approach would have turned people off."

Lakisha Vergeest, a 19-year-old from the Netherlands, said she was leaving feeling "a little bit down" and even "shocked" by pondering the scope of the global nuclear arsenal.

"15,000 is a lot," she said. "It's too much."

The Berlin film festival runs until February 19.