North Korean leader Kim Jong-un. NKnews North Korea is not denying allegations made by US officials that the country was behind a massive hack on Sony Pictures last week that took down the company's computer network.

When contacted by the BBC, a North Korean government spokesman said: "Wait and see."

A group calling itself "Guardians of Peace" broke into the servers of Sony Pictures, an international movie studio owned by Sony.

The group took over screens inside the company, stealing files and even leaking unreleased movies online. Employees were left using pens and paper to do their jobs, unable to even attempt to log on to their computers.

Here's what screens inside Sony Pictures looked like after the hack:

It's still not known exactly who the Guardians of Peace are. They say they have a source inside Sony who had similar opinions and let them inside the computer network. But US intelligence agencies aren't buying that claim.

NBC News says it has knowledge of classified briefings that suggested North Korea was a possible source of the hack. It's not completely far-fetched, as the country has been tied to hackings in the past. According to Re/code, North Korea has its own hacking army division known as Unit 121, which is widely suspected of being behind cyberattacks on South Korea and the US.

North Korea also has a motive to attack Sony Pictures. The studio is set to release "The Interview" this month, which stars Seth Rogen and James Franco as celebrity journalists who land an interview with North Korean dictator Kim Jong-un before attempting to kill him.

On June 25, North Korea's official news agency denounced the film as a "blatant act of terrorism and war." And on July 11, the country's ambassador to the UN accused the movie as being an "act of war."

An official from North Korea's London embassy refused to comment on the Sony Pictures hack, telling Business Insider that they were "not interested" in talking to the press.