North Korea has proposed a "joint investigation" into the cyber-terrorist attack on Sony.  They also say they can "prove" they're not behind the attack.

Fox News:

The announcement comes as a response to the FBI's statement saying it has enough information to “conclude that the North Korean government is responsible” for the actions.

The bureau said its findings were the result of an investigation that involved multiple departments and agencies, and were based in part on technical analysis of the malware used in the attack. The FBI said the malware "revealed links to other malware that the FBI knows North Korean actors previously developed."

Further, the FBI noticed "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 instance, the FBI said several IP addresses with "known North Korean infrastructure" communicated with IP addresses "hardcoded" into the malware that ripped through Sony's systems, deleting data and swiping sensitive information and rendering thousands of computers inoperable.

The FBI also said the "tools" used in the attack are similar to those in a North Korea-led attack against South Korean banks and media outlets last year.

"We are deeply concerned about the destructive nature of this attack on a private sector entity and the ordinary citizens who worked there," the FBI said in its statement. "Further, North Korea's attack on SPE reaffirms that cyber threats pose one of the gravest national security dangers to the United States. Though the FBI has seen a wide variety and increasing number of cyber intrusions, the destructive nature of this attack, coupled with its coercive nature, sets it apart.

"North Korea's actions were intended to inflict significant harm on a U.S. business and suppress the right of American citizens to express themselves. Such acts of intimidation fall outside the bounds of acceptable state behavior."

CNN reports on NoKo's hilarious official statement:

"Whoever is going to frame our country for a crime should present concrete evidence," the state-run Korean Central News Agency reported Saturday.

"America's childish investigation result and its attempt to frame us for this crime shows their hostile tendency towards us."

But in a rare move, the North Korean regime said both countries should work together.

"While America has been criticized by its own public and continues to point the finger at us, we suggest mutual investigation with America on this case," KCNA said.

"If America refuses our proposal of mutual investigation, continues to link us to this case, and talk about actions in response, they (America) will be met with serious consequences."

Both sides know the joint investigation is never going to happen, so the NoKo offer was window dressing.  But perhaps we should surprise them and take them up on it.  They would have to give us access to their military cyberwarfare people and share with us all relevant coding and software they use in their attacks.

That's the only way we can be convinced they aren't behind the Sony hack.

When the president says we're going to respond to this attack, does he mean we're going to counter-hack the North Korean government?  That would be an escalation that could unleash an attack on our infrastructure.  More likely, the response will be non-computer related – an admittedly weak response, but our options are limited.