North Korea has denied several times of its involvement in the series of cyber attacks against Sony Pictures Entertainment. After hearing the accusations from President Barack Obama on Friday, North Korea has called on a joint probe with the U.S. to finally resolve the issue on who was behind the attack and to also claim the country's non-participation to any of the hacking incidents that were reported.

It was said that the U.S. Federal Bureau of Investigation had made a recent announcement saying that North Korea was behind the Sony hack. According to the agency, Pyongyang's hack on Sony fell beyond what is considered as an acceptable state behavior. 

Obama said North Korea seemed to have done the attack alone. The U.S. had also begun consulting with Russia, South Korea, China and Japan to seek their assistance as the nation prepares to retaliate against North Korea.

So far, South Korea and Japan had confirmed that they would cooperate. 

According to the technical analysis done by the FBI, the malicious software that was used in the Sony attack had links to the malware that was developed by "North Korean actors." Moreover, they were found to have a "significant overlap" with malicious cyber activities which had been tied to Pyongyang in the past.

While Obama did not really specify how he plans to bounce back at the hackers, U.S. experts say that his options could include criminal indictments against those who are implicated in the attack, financial sanctions, cyber retaliation or a heightened U.S. military support to South Korea, which technically speaking, is still at odds with the North.

As a response to the U.S.' accusation, North Korea said it has a way to prove that the nation had nothing to do with the attack.  A joint investigation was then proposed by the nation which seemed to be affected by the U.S.' groundless slander and how its government had tried to mobilize public opinion.

"The U.S. should bear in mind that it will face serious consequences in case it rejects our proposal for joint investigation and presses for what it called countermeasures while finding fault with North Korea," said by a spokesman of Pyongyang. "We have a way to prove that we have nothing to do with the case without resorting to torture, as what the CIA does." 

North Korea warns of grave consequences should the U.S. refuse their proposal and continue to drag their nation into the case.