North Korea was behind the unprecedented act of cyber-warfare against Sony Pictures that drove the studio to cancel all release plans for the film at the heart of the attack, US investigators say.
The Sony hack has been connected to the isolated communist nation, according to an official.
Earlier, the besieged company cancelled the Christmas Day release of The Interview, citing the threats of violence against cinemas and decisions by the largest multiplex chains in North America to pull the film from its screens. It later said there were no further plans to release the film.
The attack was possibly the costliest yet for a US company, said Avivah Litan, a cyber-security analyst at research firm Gartner.
"This attack went to the heart and core of Sony's business - and succeeded," she said. "We haven't seen any attack like this in the annals of US history."
The movie cancellation was a startling blow to the Hollywood studio. The hackers, who call themselves Guardians of Peace, had threatened attacks reminiscent of September 11, 2001 against cinemas showing the film.
Sony then offered cinemas the option of bowing out and, one after the other, all the top US chains announced they were postponing any showings of the comedy about a pair of journalists played by James Franco and Seth Rogen tasked by the CIA to assassinate North Korea leader Kim Jong Un. Sony said it then had little choice but to cancel the release.
"We are deeply saddened at this brazen effort to suppress the distribution of a movie, and in the process do damage to our company, our employees, and the American public," Sony Pictures said.
Some of Hollywood's best-known faces took to Twitter to oppose the decision - with Ben Stiller branding it "a threat to freedom of expression". Rob Lowe, who stared in the West Wing, said: "Wow. Everyone caved. The hackers won. An utter and complete victory for them. Wow."
He compared the decision to pull the film to the former British prime minister Neville Chamberlain's policy of appeasement with Adolf Hitler.
"Saw @Sethrogen at JFK. Both of us have never seen or heard of anything like this. Hollywood has done Neville Chamberlain proud today," he tweeted.
Comedian Jimmy Kimmel branded the move an "un-American act of cowardice that validates terrorist actions and sets a terrifying precedent".
Oscar-wining screenwriter Aaron Sorkin, who has already attacked the media for spreading information leaked by the hackers, said: "Today the US succumbed to an unprecedented attack on our most cherished, bedrock principle of free speech."