President Barack Obama said the United States is reviewing whether to put North Korea back onto its lists of state sponsors of terrorism following a cyber attack on Sony Pictures, which U.S. officials blame on the communist nation.
Speaking on CNN's State of the Union, Obama said he did not consider the hack an act of war, but a "very costly, very expensive" example of cyber vandalism.
North Korea denies it was responsible for hacking Sony Pictures' computer network and posting embarrassing e-mails and other private data.
The hackers call themselves the Guardians of Peace and warned there would be a "bitter fate" for anyone attending a public showing of the movie The Interview, a film in which the CIA hires two journalists to kill North Korean leader Kim Jong Un.
Sony has canceled the scheduled December 25 release of the satirical comedy.
Not aware of hackers
On Sunday, North Korean state media reported the country's Policy Department of the National Defense Commission issued a statement saying it is not aware of the country of residence of the hackers. It said is has evidence the Obama administration was involved in the making of "The Interview" and warned that North Korea has already launched a "counteraction."
On Friday, Obama criticized the film's cancellation and warned such digital attacks are something the country will have to adapt to.
Pyongyang has said it can prove it was not involved in the attacks and has warned of "grave consequences" if Washington fails to accept the invitation to join an investigation.
The United States has rejected the offer and is in talks with China to help block cyber attacks from Pyongyang.
A U.S. official has said that both the U.S. and China agree that conducting destructive cyber attacks is outside the norm of a civilized country.
The request could be problematical because Washington has long said Chinese cyber theft has threatened U.S. defense secrets, hurt American companies' competitiveness and cost American workers jobs.
Sony Pictures chairman Michael Lynton told reporters Friday that the studio had no choice but to cancel the film's release because American theaters were unwilling to show it.
Lynton did, however, tell interviewers that Sony did not "give in" or surrender to the hackers, and is trying to find some format for people to view the film, possibly through a video-on-demand service or over the Internet.