WASHINGTON (AP) — The Obama administration says it's determined the North Korean government was behind a devastating hacking attack against Sony Pictures Entertainment.

The FBI announcement Friday is the first official statement blaming the isolated country for the cyber-attack.

In the statement, federal officials say they found similarities between the tools used in the Sony attack and previous hacks linked to North Korea.

Administration officials had previously declined to openly blame North Korea but said they were weighing various options for a response.

The break-in resulted in the disclosure of tens of thousands of leaked emails and other materials and escalated to terrorist threats that promoted Sony to cancel the Christmas release of the movie "The Interview." The comedy is about a plot to assassinate North Korean leader Kim Jong Un.

NEW: Hackers gloat over 'The Interview' cancellation in new email

Hackers have sent a new email to Sony Pictures Entertainment, praising the studio as "very wise" to cancel the release of "The Interview" and saying Sony's data is safe "as long as you make no more trouble."

The email 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.

The message warned to "never" release the film "in any form," including on DVD. The email was sent to several employees of the Culver City, California company.

The Obama administration on Friday formally accused the North Korean government of being responsible for the devastating hacking attack.