The United States is pretty sure that a cyberattack against Sony Pictures was the doing of the North Korean government, a spokesman for the White House National Security Council said Saturday.

"As the FBI made clear, we are confident the North Korean government is responsible for this destructive attack. We stand by this conclusion," a spokesman for the White House National Security Council said Saturday. 

Pyongyang had earlier denied that it was involved in the hacking of Sony Pictures computers and offered a "joint investigation" into the attack.

"The government of North Korea has a long history of denying responsibility for destructive and provocative actions," Mark Stroh said.

The FBI had earlier on Friday singled out the North Korean government for being behind a cyber attack onSony Pictures that resulted in droves of sensitive and confidential information being made public.

The hackers, known as the Guardians of Peace, also threatened 9/11-style attacks on theaters showing "The Interview." The movie's plot involves a television industry duo that is recruited by the CIA to kill North Korean dictator Kim Jong-Un.

President Barack Obama said the U.S. "will respond proportionally, and we'll respond in a place and time and manner that we choose.” 

Anadolu Agency