North Korea has described new sanctions imposed in response to a major cyber-attack against Sony Pictures as part of a hostile and inflammatory US policy.
The US placed sanctions on three North Korean organisations and 10 individuals after the FBI blamed Pyongyang for the cyber-attack.
North Korea praised the attack on Sony but denied any involvement in it.
It came as Sony was about to release The Interview, a comedy about a plot to assassinate North Korea's leader.
Sony initially cancelled plans to show the film, before deciding to release it online and at a limited number of cinemas.
The US sanctions imposed on Friday are believed to be the first time the US has moved to punish any country for cyber-attacks on a US company.
Announcing them, White House officials told reporters the move was in response to the Sony hack, but the targets of the sanctions were not directly involved.
In response, the North's state-run KCNA news agency on Sunday quoted a foreign ministry spokesman as saying: "The policy persistently pursued by the US to stifle the DPRK [North Korea], groundlessly stirring up bad blood towards it, would only harden its will and resolution to defend the sovereignty of the country.
"The persistent and unilateral action taken by the White House to slap 'sanctions' against the DPRK patently proves that it is still not away from inveterate repugnancy and hostility toward the DPRK."
Analysis by BBC East Asia specialist Charles Scanlon
The North Korean statement says the US allegations that it was involved in the Sony hack are absurd, and it points to cyber experts in the West who also doubt its involvement.
It says the US has been stung by the growing international scepticism and imposed sanctions to try to save face.
North Korea warns the sanctions will be counter-productive as they encourage it to strengthen its military stance, including, by implication, its nuclear arsenal.
But the involvement of the US Treasury Department in the measures is likely to cause some anxiety in Pyongyang. It has shown an ability in the past to disrupt revenue streams that are directly linked to the leadership.
US sanctions were already in place over North Korea's nuclear programme but analysts said the new sanctions were designed to further isolate the country's defence industry.
Those named in the sanctions were:
- The Reconnaissance General Bureau, North Korea's primary intelligence organisation
- North Korea's primary arms dealer, the Korea Mining Development Trading Corporation (Komid)
- Korea Tangun Trading Corporation, which supports North Korea's defence research
- Jang Song Chol, a government official said to be a Komid representative in Russia
- Kim Yong Chol, a government official said to be a Komid representative in Iran
- Ryu Jin and Kang Ryong, both Komid officials in Syria, according to the US
North Korea blamed the US for lengthy internet outages in the country last week but US officials have not commented on any possible American involvement.
Sony hack: The Interview saga
The Interview features James Franco and Seth Rogen as two journalists granted an audience with Mr Kim. The CIA then enlists the pair to assassinate him.
- 22 November: Sony computer systems hacked, exposing embarrassing emails and personal details about stars
- 7 December: North Korea denies accusations that it is behind the cyber-attack, but praises it as a "righteous deed"
- 16 December: "Guardians of Peace" hacker group threatens 9/11-type attack on cinemas showing film; New York premiere cancelled
- 17 December: Leading US cinema groups say they will not screen film; Sony cancels Christmas Day release
- 19 December: FBI concludes North Korea orchestrated hack; President Obama calls Sony cancellation "a mistake"
- 20 December: North Korea proposes joint inquiry with US into hacks, rejected by the US
- 22 December: North Korea suffers a severe internet outage
- 23 December: Sony confirms a limited Christmas Day release for The Interview
- 2 January: The US imposes sanctions on North Korea in response to the cyber-attack.