A day after the U.S. concluded that North Korea was responsible for a massive hacking attack against Sony Pictures Entertainment, the isolated totalitarian regime responded Saturday by denying responsibility and proposing a joint investigation into the attack -- and it warned of "serious consequences" if Washington refused to cooperate.
"The U.S. should bear in mind that it will face serious consequences in case it rejects our proposal for joint investigation and presses for what it called countermeasure while finding fault with the [Democratic People's Republic of Korea]," a spokesman for North Korea's foreign ministry told state media KCNA on Saturday.
The FBI concluded Friday that North Korea was behind the Sony hack, which has targeted senior executives at the company, celebrities, and exposed sensitive records of studio employees. "We are deeply concerned about the destructive nature of this attack on a private sector entity and the ordinary citizens who worked there," the FBI said in a statement.
The U.S. has requested help from China to address the hacking attack. "We have discussed this issue with the Chinese to share information, express our concerns about this attack, and to ask for their cooperation," a senior administration official told NBC News' Kristen Welker. "In our cybersecurity discussions, both China and the United States have expressed the view that conducting destructive attacks in cyberspace is outside the norms of appropriate cyber behavior."
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North Korea said the U.S. is "slandering Pyongyang by spreading unfounded rumors," adding, "We have a way to prove that we have nothing to do with the case without resorting to torture as what the CIA does."
Mark Stroh, a spokesman for the National Security Council, said the U.S. stands by its conclusion that North Korea is responsible for the hack and noted that the country has a "long history of denying responsibility for destructive and provocative actions."
"If the North Korean government wants to help, they can admit their culpability and compensate Sony for the damages this attack caused," Stroh said.
"The U.S. should bear in mind that it will face serious consequences in case it rejects our proposal for joint investigation."'
A shadowy hacker group calling itself the "Guardians of Peace" has claimed responsibility for the attack, and the cyber disruption led to Sony canceling its release of "The Interview," a satirical movie staring Seth Rogen and James Franco that centers around a plot to assassinate North Korean leader Kim Jong Un. Sony's move came after a number of the largest U.S. movie theater chains decided not to screen the movie after hackers threatened violence against theaters showing the film.
The United States has promised a response, but officials have not detailed any specific moves.
“Sony is a corporation, it suffered significant damage, threats against employees,” President Obama told reporters Friday at a year-end White House press conference. "I am sympathetic to the concerns that they faced. Having said all that, yes, I think they made a mistake."
The president warned against allowing a "dictator" to impose censorship in the United States. "Because if somebody is able to intimidate folks out of releasing a satirical movie, imagine what they start doing when they start seeing a documentary they don’t like or news reports they don’t like. “
Obama added that he wished Sony has spoken to him first before deciding to pull the movie. "I would have told them: 'Do not get into a pattern in which you're intimidated by these kinds of criminal attacks,'" he said.
Sony CEO Michael Lynton pushed back on the criticism from the president, as well as a number of celebrities who have spoken out against the studio's move, telling CNN Friday in an exclusive interview that his company's critics are "mistaken."
Related: Sony CEO strikes back: ‘We have not caved’
Lynton also said the studio did reach out to the White House to discuss the cyberattack. "We definitely spoke to senior advisors … whether we spoke to the president himself … the White House was definitely aware of the situation,” he said.