US Officially Accuses North Korea of Sony Hacking

The Obama administration on Friday formally accused North Korea's government of being responsible for the dramatic hacker break-in at Sony Pictures Entertainment Inc. but offered few hints about how or whether it would retaliate. Its proof:

The U.S. detected communications between computer Internet addresses known to be operated by North Korea and hacking tools left behind at the crime scene, which the FBI also said contained subtle clues linking them to that country's government.

The decision to openly blame North Korea ? which involved the State Department and U.S. intelligence agencies ? escalated an intriguing global game of brinkmanship that included the disclosure of confidential Sony emails and business files and threats of terror attacks against U.S. movie theaters until Sony agreed to cancel the Christmas Day release of its comedy, "The Interview," which the hackers had demanded partly over a scene depicting the assassination of North Korea's leader.

The FBI described the Sony hacking as unusual because of "the destructive nature of this attack, coupled with its coercive nature."

"The FBI now has enough information to conclude that the North Korean government is responsible for these actions," said the U.S. statement, which was not attributed to any official by name. It added: "North Korea's actions were intended to inflict significant harm on a U.S. business and suppress the right of American citizens to express themselves."

The statement did not suggest how or whether the Obama administration would respond but included a general promise to impose "costs and consequences" against any person, group or government using cyberattacks to threaten the U.S. or its interests.

North Korea has denied it was involved but praised the hacking as a "righteous deed." On Friday, a North Korean diplomat to the United Nations, Kim Un Chol, declined to comment on the American accusations.

In a taunting new email the hackers sent to Sony, they told the Hollywood studio that executives were "very wise" to cancel the movie's release and said they planned no further disclosures of Sony's confidential materials "as long as you make no more trouble." The message warned "never" to release the film "in any form," including on DVD. The email was sent to several employees. It was confirmed Friday by a person close to the studio who requested anonymity because the person wasn't authorized to speak publicly about the matter.

In Hollywood, actor George Clooney said the entertainment industry should take action now by pushing for the immediate release of "The Interview" online. In an interview with the trade site Deadline, Clooney urged Sony to "stick it online. Do whatever you can to get this movie out. Not because everybody has to see the movie, but because I'm not going to be told we can't see the movie. That's the most important part."

President Barack Obama was expected to be asked about the hacking at a news conference later Friday.