The FBI might be keeping a closed-door approach to the Sony Pictures hack in the public, but privately the agency is seeking the help of security experts, who question North Korea's involvement in the attack.

Ever since U.S. officials linked the Sony Pictures attack to North Korea, security groups have been hot on the trail, trying to find evidence of a connection. The U.S. government continues to keep evidence linking the two groups undisclosed, adding more fuel to the fire.

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This week, the FBI held a three hour briefing to discuss the potential of laid-off Sony Pictures staff orchestrating the attack, with the help of hackers connected to the disbanded LulzSec group. 

Security groups claim this is the most likely candidate for attacker, considering the mass layoffs coming to Sony Pictures in the coming weeks, making employees more likely to strike back at the company. 

It also matches with the original statement from #GOP — the hacking group responsible for the attack — who claimed to have internal employees working to take down Sony Pictures.

The attackers spoke of "inequality" before North Korea entered the conversation, then #GOP quickly changed its rhetoric to disguise itself, according to cyber intelligence firm Norse.

Other intelligence groups claim the attack may have been pulled off by Chinese or Russian hackers, and a linguistics firm points to Russian hackers as prime suspects, after deciphering the messages sent to Sony Pictures. 

Several political commentators have likened the U.S. government's response to the same hasty Iraq response, when claiming the country was hiding weapons of mass destruction.

If the U.S. is not willing to give up the connection to North Korea, it may be due to a political agenda to halt North Korea's progress. The communist state has been investing heavily in nuclear and communication technology, and new sanctions could stop the rate of growth.

TagsNorth Korea, U.S. Government, FBI, Sony Pictures, hacking, LulzSec