The hackers who claimed responsibility for the Sony Pictures cyberattack appear to have issued a new message, this time delivering a "gift" for the FBI.
The group, which calls itself Guardians of Peace, posted the message on the file-sharing website Pastebin Saturday.
"The result of investigation by FBI is so excellent that you might have seen what we were doing with your own eyes," the message read. "We congratulate you success. FBI is the BEST in the world."
A link to a two-minute YouTube video called "you are an idiot" was also included, described as "the gift for FBI." The video appears to have been originally posted on Sept. 29, 2006. It had been watched nearly half a million times by Saturday afternoon.
On Friday, the FBI declared the North Korean government was responsible for the cyberattack on Sony. Investigators said the hackers used the login credentials of a Sony computer system administrator to access the company's network. Once logged in, the hackers wiped out hard drives, stole personal data and revealed embarrassing e-mails.
After receiving threats of additional attacks that referenced the Sept. 11, 2001, terrorist attacks, Sony canceled the Christmas Day release of the movie "The Interview." The comedy is about a plot to assassinate North Korean leader Kim Jong Un.
On Friday, President Obama said that Sony "made a mistake" in shelving the satirical film and pledged that the U.S. would respond "in a place and manner and time that we choose."
North Korea on Saturday proposed a joint investigation with the U.S., warning of "serious" consequences if Washington rejects a probe that it believes would prove Pyongyang had nothing to do with the cyberattack.
National Security Council spokesman Mark Stroh responded by saying the U.S. stood by the FBI's conclusion.
"The government of North Korea has a long history of denying responsibility for destructive and provocative actions," Stroh said in a statement. "If the North Korean government wants to help, they can admit their culpability and compensate Sony for the damages this attack caused."