The North Korean government has threatened to "stand in confrontation with the US in all war spaces" as the diplomatic row over a Sony film continues to escalate.
In a strongly-worded statement, officials branded America as "an ill-famed cesspool of injustice and terrorism" and warned that "tough counteraction will be boldly taken against the White House, the Pentagon and the whole US mainland".
Despite being accused by the US of being behind the Sony hacking, the secretive state continues to insist it had no involvement.
But Pyongyang praised the "surprisingly sophisticated, destructive and threatening cyber warfare" inflicted on the company, as the movie "dared to hurt the dignity of the supreme leadership of the DPRK".
Meanwhile, South Korea has claimed one of its nuclear power plants fell victim to hacking, but stressed no reactors were affected. The developed country has not implicated North Korea in the attack.
The Interview, which included the fictional assassination of leader Kim Jong-Un, was pulled from cinemas before its release after hackers threatened to target those who went to see the film.
A story from the Korean Central News Agency said: "The Interview is undesirable and reactionary. It should not be allowed in any country or any region. The movie has a story agitating a vicious and dastardly method of assassinating a legitimate head of state.
"DPRK is praising the 'guardians of peace' for their righteous deed which prevented in advance the evil cycle of retaliation – terrorism sparks terrorism."
The Pyongyang government claims it is taking a stand "on the US gangster-like behaviour against it" – and alleges it has clear evidence that American authorities were deeply involved in the movie's production, as it would be "effective propaganda against North Korea".
Its statement said: "The facts glaringly show that the US is the chief culprit of terrorism as it has loudly called for combating terrorism everywhere in the world, but schemed behind the scenes to produce and distribute movies inciting it.
"Nothing is a more serious miscalculation than guessing that just a single movie production company is involved. Our target is all the citadels of the US imperialists who earned the bitterest grudge of Koreans.
"The US should reflect on its evil doings that put itself in such a trouble, apologise to the Koreans and other people of the world, and should not dare pull up others."
North Korea's only significant ally, China, condemned the use of cyber-attacks and cyber-terrorism early on Monday – but stopped short of criticizing the state.
President Obama, along with his advisers, is weighing up how to punish North Korea. The FBI concluded that Pyongyang was behind the Sony hacking – the first time that the US has accused another country of orchestrating such a significant cyber-attack.
David Boies, Sony's lawyer, has insisted the embattled entertainment company still plans to release its controversial film - but warned the hack was "a national security problem" and the US government needed to take the lead.
"How it's going to be distributed, I don't think anybody knows quite yet. But it's going to be distributed," he told NBC.