We will not use nukes unless attacked, vows Kim Jong Un
North Korean leader Kim Jong Un has insisted he would not use nuclear weapons unless the country was under threat.
Kim said he was ready to improve ties with "hostile" nations and called for more talks with rival South Korea to reduce misunderstanding and distrust.
Speaking at the third day of his party's congress in Pyongyang, he also urged the US to stay away from inter-Korean issues.
"Our republic is a responsible nuclear state that, as we made clear before, will not use nuclear weapons first unless aggressive hostile forces use nuclear weapons to invade our sovereignty," Kim said in a three-hour speech.
At the congress, he also announced a five-year plan, starting this year, to develop the North's moribund economy and identified improving the country's power supply and increasing its agricultural and light-manufacturing production as critical parts of the programme. He also said the country must secure more electricity through nuclear power.
It was first time that North Korea has announced a five-year plan since the 1980s and detailing it in such a public way demonstrated that Kim is taking ownership of the country's economic problems, something that his father, Kim Jong Il, avoided as leader.
Kim stressed that the country needs to increase its international trade and engagement in the global economy, but he did not announce any significant reforms or plans to adopt capitalist-style marketisation.
Market-style business has become more common in North Korea, in large part because of its economic crisis and famine in the 1990s, which made it impossible for the government to provide its citizens with the necessities they had come to rely on and forced many to learn how to fend for themselves.
But while the realities on the ground have shifted, officials have been reluctant to formally embrace significant reforms.
Kim said that North Korea "will sincerely fulfill its duties for the non-proliferation of nuclear weapons and work to realise the denuclearisation of the world".
The North is ready to improve and normalise ties with countries hostile to it if they respect its sovereignty and approach it in a friendly manner, he said.
Despite the talks about more diplomatic activity, Kim also made it clear that the North has no plans to discard its "byongjin" policy of simultaneously developing its nuclear weapons and its domestic economy.
In a speech published by the North's Rodong Sinmun newspaper, Kim described the twin policy as a strategy the party must permanently hold on to for the "maximised interest of our revolution".
Many outside analysts consider the policy unlikely to succeed because of the heavy price North Korea pays for its nuclear programme in terms of international sanctions that keep its economy from growing.
North Korea carried out its fourth nuclear test in January and followed with a satellite launch in February that was seen by outside governments as a banned test for long-range missile technology and which brought tougher UN sanctions.