The FBI has said it has determined the North Korean government was behind a devastating hacking attack against Sony Pictures Entertainment.
The announcement is the first official statement blaming the isolated country for the cyber-attack.
In the statement, federal officials said they found similarities between the tools used in the Sony attack and previous hacks linked to North Korea.
"North Korea's actions were intended to inflict significant harm on a US business and suppress the right of American citizens to express themselves. Such acts of intimidation fall outside the bounds of acceptable state behavior,'' the statement said.
Obama 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 prompted 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.