PYONGYANG - The Democratic People's Republic of Korea (DPRK) vowed Friday to take "strong physical countermeasures" if the Republic of Korea (ROK) is directly involved in the UN sanctions, which would be seen as "a declaration of war" against Pyongyang.

"We declare complete nullification of the Joint Declaration on Denuclearization on the Korean Peninsula adopted in 1992 and its total invalidity," the Committee for the Peaceful Reunification of Korea said said in a statement.

As long as the ROK persistently pursues a hostile policy, the DPRK will never negotiate with anyone, it said.

The committee also reiterated that the country would react to provocation with immediate retaliatory blows and a war of justice for national reunification.

On Tuesday, the UN Security Council unanimously approved Resolution 2087 which requires the DPRK to comply with all relevant resolutions approved by the Security Council and not to use ballistic missile technology for any launch.

It also reiterated to seek a peaceful, diplomatic and political solution to the issues concerned and advocated the renewal of the six-party talks over the denuclearization issue on the Korean Peninsula.

Both ROK and the United States have pledged to implement provisions of the UN resolution.

Rejecting the resolution, the DPRK on Thursday vowed to conduct more rocket launches and a higher-level nuclear test targeting its "sworn enemy" -- the United States.

On December 12 last year, the official KCNA news agency confirmed that the DPRK launched and orbited the second version of the Kwangmyongsong-3 satellite. After the launch, the DPRK has defended its right to launch satellites for peaceful and scientific purposes.