(Reuters) - The United States on Friday blamed North Korea for the devastating cyberattack against Sony Pictures, formally acknowledging the involvement of the Pyongyang government and saying the tools and infrastructure used in the attack were similar to previous activity from North Korea.
The "destructive nature" of the attack, which led the big Hollywood studio to pull a movie depicting North Korea's leader amid threats, coupled with "its coercive nature," set it apart from previous attacks, the FBI said.
President Barack Obama was expected to address the issue at a 1:30 p.m. (1830 GMT) end-of-year news conference.
"As a result of our investigation, and in close collaboration with other U.S. government departments and agencies, the FBI now has enough information to conclude that the North Korean government is responsible for these actions," the FBI said in a statement.
"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," it said. "Such acts of intimidation fall outside the bounds of acceptable state behavior."
The FBI said technical analysis of malware used in the Sony attack found links to malware that "North Korean actors" had developed and found a "significant overlap" with "other malicious cyber activity" previously linked to Pyongyang.
North Korea has previously denied involvement, and a North Korean U.N. diplomat on Thursday declined to comment on the accusation that Pyongyang was responsible.
"Working together, the FBI will identify, pursue, and impose costs and consequences on individuals, groups, or nation states who use cyber means to threaten the United States or U.S. interests," said the FBI, the Federal Bureau of Investigation.
It stopped short of threatening specific U.S. action.
POSSIBLE U.S. RESPONSES
U.S. experts say options for the Obama administration could include cyber retaliation, financial sanctions and even a boost in U.S. military support to South Korea to send a stern message to North Korea. But the effect of any response could be limited given North Korea's isolation and the fact that it is already heavily sanctioned.
The attack on Sony more than three weeks ago, the most destructive hacking of a company on U.S. soil, was conducted by hackers calling themselves "Guardians of Peace."
It brought down the computer network at Sony Pictures Entertainment, prompted the leak of embarrassing emails, and led to Sony's cancellation of the Christmas Day release of "The Interview," a comic film that culminates in a scene depicting the assassination of North Korean leader Kim Jong Un.
U.S. movie theaters had said they would not show the film after hackers made threats against cinemas and audiences. Many in Hollywood and Washington criticized Sony's cancellation as caving in to the hackers.
Sony Pictures is a unit of Sony Corp (6758.T).
(Writing by Matt Spetalnick, additional reporting by Susan Heavey in Washington and Ju-min Park and Jack Kim in Seoul, Editing by David Storey)
