North Korea has promised to strengthen its nuclear weapons, saying they were the "life of the nation" and would not be traded, even for "billions of dollars".
A day after Pyongyang declared it was in a state of war with South Korea, the regime's politburo defied the latest international sanctions by setting out a twin strategy for the year.
Its aim will be "carrying out economic development and building nuclear armed forces simultaneously".
The Korean Central News Agency said nuclear weapons "can never be abandoned as long as imperialists and nuclear weapons exist on Earth".
It added that the country would not negotiate over its atomic programme, which was a "treasure" and not a "political bargaining chip" to be abandoned for any amount of aid.
With tensions on the Korean peninsula running high, there was a warning that the North would pursue further "satellite tests", a programme that the West believes is a covert excuse to test its long-range missiles.
In recent weeks, the North has made almost daily threats, including a vow to launch nuclear strikes on the US, which followed a new round of UN sanctions in reaction to its third nuclear test last month.
The latest outburst was probably a response to annual American-South Korean military drills, which included a dummy bombing raid by a US B-2 stealth bomber last week.
A full-scale military attack by the North is seen as unlikely, and the threats could be designed to project the credentials of Kim Jong-un, the young leader, or bring about a resumption of talks and more aid.
International powers are nonetheless concerned that a small spark could provoke a major incident.
The capital of the south, Seoul, has only one nuclear bunker, and while it claims that more than 20 million people can hide underground from an attack, in reality its shelters are merely skyscraper basements and underground stations.
Experts say hundreds of lives could be lost if the artillery dug into the hills north of the demilitarised zone opened fire. Estimates put the number of deaths at up to two million in the case of a nuclear attack.
Among the people of Seoul, only 30 miles from the border, there is little concern about heated rhetoric.
Yongja Kim (69) said: "They are just trying to create fear."
Wooseok Shin (79), who can point to the scars on his face and hands left by the bayonets of North Korean soldiers six decades ago, is adamant that there will be no further fighting.
"What North Korea is up to now is psychological warfare," he said. "They are simply being provocative to win more economic aid." (© Daily Telegraph, London)