A top North Korean decision-making body has issued a pointed warning, saying that nuclear weapons are "the nation's life" and will not be traded even for "billions of dollars".
The comments came in a statement released after North Korean leader Kim Jong Un presided over the plenary meeting of the central committee of the ruling Workers' Party.
The meeting, which set a "new strategic line" calling for building both a stronger economy and nuclear arsenal, comes amid a series of near-daily threats from Pyongyang in recent weeks, including a vow to launch nuclear strikes on the United States and a warning on Saturday that the Korean Peninsula was in a "state of war".
Pyongyang is angry over annual US-South Korean military drills and a new round of UN sanctions that followed its February 12 nuclear test, the country's third.
Analysts see a full-scale North Korean attack as unlikely and say the threats are more likely efforts to provoke softer policies towards Pyongyang from a new government in Seoul, to win diplomatic talks with Washington that could get the North more aid, and to solidify the young North Korean leader's image and military credentials at home.
North Korea made reference to those outside views in the statement it released through the official Korean Central News Agency following the plenary meeting.
North Korea's nuclear weapons are a "treasure" not to be traded for "billions of dollars," the statement said. They "are neither a political bargaining chip nor a thing for economic dealings to be presented to the place of dialogue or be put on the table of negotiations aimed at forcing (Pyongyang) to disarm itself," it said.
North Korea's "nuclear armed forces represent the nation's life, which can never be abandoned as long as the imperialists and nuclear threats exist on earth," the statement said.
North Korea has called the US nuclear arsenal a threat to its existence since the 1950-53 Korean War, which ended in a truce, not a peace treaty, leaving the peninsula still technically at war. Pyongyang justifies its own nuclear pursuit in large part on that perceived US threat.
While analysts call North Korea's threats largely brinkmanship, there is some fear that a localised skirmish might escalate. Seoul has vowed to respond harshly should North Korea provoke its military. Naval skirmishes in disputed Yellow Sea waters off the Korean coast have led to bloody battles several times over the years. Attacks blamed on Pyongyang in 2010 killed 50 South Koreans.