According to a statement issued by the FBI on December 19, which was then echoed by President Obama during his year-end press conference, “the North Korean government is responsible” for hacking Sony’s servers, leaking sensitive company data online, threatening movie theaters that choose to exhibit the satire The Interview, and ultimately succeeding in getting the Kim Jong Un assassination comedy’s release pulled.

The FBI presented the following as evidence:

“Technical analysis of the data deletion malware used in this attack revealed links to other malware that the FBI knows North Korean actors previously developed. For example, there were similarities in specific lines of code, encryption algorithms, data deletion methods, and compromised networks.

The FBI also observed significant overlap between the infrastructure used in this attack and other malicious cyber activity the U.S. government has previously linked directly to North Korea. For example, the FBI discovered that several Internet protocol (IP) addresses associated with known North Korean infrastructure communicated with IP addresses that were hardcoded into the data deletion malware used in this attack.

Separately, the tools used in the SPE attack have similarities to a cyber attack in March of last year against South Korean banks and media outlets, which was carried out by North Korea.”

Meanwhile, North Korea has maintained their stance that they weren’t involved in the crippling cyber-attack, and have proposed a joint investigation with the U.S. authorities in finding the culprits, warning of “grave consequences” if America continues to blame the Hermit Kingdom for the hacking.

On Saturday afternoon, Guardians of Peace, the hacking group that’s so far claimed responsibility for wreaking havoc on Sony, posted a message online mocking the FBI’s investigation.

It is as follows:

“By GOP

The result of investigation by FBI is so excellent that you might have seen what we were doing with your own eyes.

We congratulate you success.

FBI is the BEST in the world.

You will find the gift for FBI at the following address.”

Then, they included a link to the following video titled “you are an idiot!”—essentially Rickrolling the FBI. The video opens with some words in Japanese, before cutting to a series of gyrating animated bodies shrieking, "You are an idiot!"

While the FBI, President Obama, and George Clooney seem thoroughly convinced that the Guardians of Peace are the work of Pyongyang—the name “Guardians of Peace” comes from a quote used by former President Richard Nixon describing South Korea—many hackers online have questioned the allocation of blame from Day One, including former Lulzsec hacker turned government information Sabu, who maintains they “don’t have the technical capabilities,” and Anonymous, who wrote, “we all know the hacks didn't come from North Korea,” and threatened to launch further hacks against Sony if they don't release the film online. Some of the world’s leading cybersecurity experts have also questioned whether North Korea is responsible for hacking Sony, claiming a decided lack of evidence or that it came from a group posing as North Korea as misdirection, such as Brett Thomas, chief technology officer of Redwood City, California-based online services company Vindicia:

President Obama, meanwhile, seems quite adamant in believing the narrative that North Korea and its leader, Kim Jong Un, were so offended by the satire The Interview, a Seth Rogen and James Franco flick which portrays the Dear Leader being assassinated, that they launched a cyber-attack on Sony as retribution, and threatened a “proportional” response by the U.S.

“The FBI announced today and we can confirm that North Korea engaged in this attack,” President Obama announced during his year-end presser on Friday. “I think it says something interesting about North Korea that they decided to have the state mount an all-out assault on a movie studio because of a satirical movie starring Seth Rogen and James Flacco [Franco]. I love Seth and I love James, but the notion that that was a threat to them I think gives you some sense of the kind of regime we’re talking about here.”

He added, “They caused a lot of damage, and we will respond. We will respond proportionally, and we’ll respond in a place and time and manner that we choose. It’s not something that I will announce here today at a press conference.”