North Korea's top ruling organ on Wednesday declared a "retaliatory" campaign against the United States, threatening to use miniaturized nuclear weapons and cyber warfare means.
  

The National Defense Commission stressed Pyongyang is not interested in talks with Washington, which it claims is bent on bringing down the communist regime.
  

"Now that the gangster-like U.S. imperialists' military strategy towards the DPRK is inching close to the stage of igniting a war of aggression, the just counteraction of the army and people of the DPRK will be focused on inflicting the bitterest disasters upon the United States of America," it said in a English-language statement.
  

The DPRK is the acronym of the North's formal name, the Democratic People's Republic of Korea.
  

It strongly criticized President Barack Obama for introducing a set of additional sanctions on Pyongyang and publicly saying the isolated nation is doomed to collapse.
  

The commission also cited the U.S. plans to begin annual joint military drills with South Korea in March on the peninsula as a token of its hostile policy.
  

"It is the decision of the army and people of the DPRK to have no longer the need or willingness to sit at the negotiating table with the U.S. since the latter seeks to stamp out the ideology of the former and 'bring down' its social system," the commission said.
  

The North's military will ratchet up its "retaliatory action of justice" by use of every possible mean, including the nation's "smaller, precision and diversified" nuclear striking means and cyber warfare capabilities, it added.
  

The U.S. "should be mindful that the time of nightmares is coming nearer when they will meet the most disastrous, final doom on the U.S. mainland," the commission warned, saying the statement was issued at "the authorization," apparently meaning the instruction, of leader Kim Jong-un.
  

Pyongyang's renewed strong threat came days after the two sides lost a chance for dialogue. The U.S. offered bilateral talks in a third nation while its chief nuclear envoy Sung Kim was on a trip to Northeast Asia earlier this week.
  

But the North counter-proposed that Kim visit Pyongyang, which was rejected by Washington.
  

South Korea said it will continue efforts to improve ties with the North, despite the stand-off between Pyongyang and Washington.
  

"There is no change in the government's basic stance that in separation (with the situation) it will strive to build trust between South and North Korea through dialogue and cooperation and developing inter-Korean relations, as well as bringing peace to the Korean Peninsula and establishing the ground for reunification," unification ministry's spokesman Lim Byeong-cheol said at a press briefing.
  

In recent weeks, U.S. officials have been active in seeking to assure media here that the allies are on the same page over the North Korea issue. Not long before the South's presidential panel suggested condition-free ministerial talks with the North, the Obama administration announced new sanctions on Pyongyang.
 

The world is paying keen attention to whether the secretive North has actually developed the technology to mount a nuclear bomb on a missile.
  

It has conducted three known underground nuclear tests in 2006, 2009 and 2013. It also succeeded in sending a long-range rocket into orbit in late 2012.
  

The North's cyber threat is another serious concern for the international community, with the U.S. saying its regime was behind a recent hacking of Sony Pictures. (Yonhap)