By Alex Altman and Zeke J Miller
Updated: December 19, 2014 2:06 PM ET

The FBI on Friday accused the North Korean government of being behind the devastating hack on Sony Pictures Entertainment that eventually prompted it to cancel the release of The Interview, the first formal statement that the U.S. government has concluded the isolated nation is responsible for the cyberattack.

“The FBI now has enough information to conclude that the North Korean government is responsible,” the bureau said in a statement. “Though the FBI has seen a wide variety and increasing number of cyber intrusions, the destructive nature of this attack, coupled with its coercive nature, sets it apart.”

President Barack Obama, asked Friday about Sony’s decision to pull The Interview, said: “Yes, I think they made a mistake”

The FBI said it determined North Korea was responsible based on an analysis of the malware involved and its similarities to previous attacks the U.S. government has attribute to North Korean-allied hackers, including an assault on South Korean banks and media outlets in 2013. These include “similarities in specific lines of code, encryption algorithms, data deletion methods, and compromised networks,” the FBI said in its statement. According to the FBI, the malware used in the attack communicated with known North Korean computers. The FBI didn’t furnish evidence to back its assertion that North Korea was involved. North Korea has denied being behind the hack.

Read more: The 7 most outrageous things we learned from the Sony hack

Bureau investigators have been working for weeks with Sony executives and private security experts to investigate the scale and origins of the attack. For Sony, the hack has been devastating: It crippled the studio’s infrastructure, leaked sensitive documents about tens of thousands of employees and contractors, embarrassed executives and resulted in the studio’s decision to pull, The Interview, a movie whose plot centers around the assassination of North Korean leader Kim Jong Un. The film incensed the North Korean government.

Read more: 4 things every single person can learn from the Sony hack

The FBI did not say whether the attack was coordinated from within North Korea or through allies outside the hermit kingdom. The FBI said it could only provide limited information to the public to protect its sources and methods.

President Barack Obama is expected to address the incident on Friday afternoon in a White House news conference. On Thursday, White House Press Secretary Josh Earnest said the administration was treating the incident as a “serious national security matter.”

White House officials have convened daily meetings to discuss the attack and to devise options for a “proportional response,” Earnest said, not ruling out an American counter-attack on North Korean systems.

“The FBI’s announcement that North Korea is responsible for the attack on Sony Pictures is confirmation of what we suspected to be the case: that cyber terrorists, bent on wreaking havoc, have violated a major company to steal personal information, company secrets and threaten the American public,” Chris Dodd, who heads the trade group Motion Picture Association of America, said in a statement. “It is a despicable, criminal act.”

See the full FBI statement:

Write to Alex Altman at alex_altman@timemagazine.com.

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