The Chernobyl nuclear disaster was ordered deliberately by Moscow, as a coverup to distract attention from a failed weapons project.

That's the seemingly wild-eyed conspiracy theory behind a highly topical new film that takes direct aim at Russia, including over its post-Soviet aggression.

"The Russian Woodpecker," screened at the Sundance Film Festival this weekend, tells the tale of a Ukrainian artist's bid to find out what actually caused the 1986 catastrophe in the then Soviet republic.

And its US director Chad Gracia uses the personal story to warn of the dangers by Russia's continued warmongering in its former sphere, over three decades after the end of the Cold War.

"Putin's strategy is to ensure that there are a ring of failed states around Russia," Gracia told AFP in an interview, adding: "Putin holds all the cards. He has nuclear weapons. He has a huge army.

"All those things are in Putin's favor," said the director, who uses extensive footage of Ukrainian street protests that preceded Ukraine's current bloody struggle with pro-Russia separatists.

The "Russian Woodpecker" of the film's title refers to a notorious rat-a-tat (hence the name) radio signal that started being beamed to the West from the Soviet Union in the 1970s.

- Mysterious structure -

Artist Feder Alexandrovich, whose family had long been victim of Moscow's abuse and the Great Famine of the 1930s, became fascinated by the bizarre signals when he began investigating the real cause of the Chernobyl disaster.

Specifically, he traced it to a massive mysterious structure built near the doomed nuclear power plant, site of the world's worst civilian nuclear disaster.

His theory, in a nutshell: the structure and signal were part of some long-running weapons project that was failing. And to distract attention from the failure, the official responsible ordered the Chernobyl meltdown.

"I'm a skeptic at heart," Gracia said of Alexandrovich's analysis.

But he added: "There certainly was a coverup over Chernobyl, I have no doubt about that... whether Fedor's theory is correct or some form of it, until the archives are open, it can only remain a theory."

Alexandrovich, who accompanied the director to the prestigious film festival in the Utah mountain resort of Park City, said he can understand those who are doubtful.

"As an artist and a Ukrainian, I am confident in my theory. But for the rest of the world to take it seriously, everyone has to be united and demand an investigation," he told AFP.

- World War III? -

But he agreed with Gracia that the greater priority is stopping what he described as Russia's continuing aggression in his homeland, which he says is part of a long-standing pattern.

"If Putin was stopped in Chechnya, then there wouldn't be (the brief 2008 war in) Georgia. If he was stopped in Georgia, there wouldn't be Ukraine," he said.

"If it's not possible to beat him in Ukraine, then the next step for him would be the war against NATO. He wouldn't even think that he's starting World War III, but he would begin it."

Gracia said Russia's annexation of Crimea and the current fighting in eastern Ukraine are just the natural progression from Moscow's historical aggression in its former Soviet area.

"To me, it vindicates the film. Fedor has said 'Every time I make a statement, I hope I'm wrong.' But unfortunately so far, he's been right," Gracia said.

Bizarrely, after filming had wrapped up on the movie, the mysterious "Russian Woodpecker" signals began being beamed again, this time aimed at Europe rather than the United States.

"It is saber-rattling. It's Putin reminding the West that he's still there, that he's watching," he said.

"It's a symbol that we're not living in a world where we're allies. We're living in a world that much more closely resembles the Cold War."