North Korea has said it would immediately suspend nuclear and missile tests, scrap its nuclear test site and instead pursue economic growth and peace, ahead of planned summits with South Korea and the United States.
The move has been welcomed by the United States, China and the EU.
North Korean leader Kim Jong Un said his country no longer needed to conduct nuclear tests or intercontinental ballistic missile tests because it had completed its goal of developing the weapons, the state-run Korean Central News Agency (KCNA) said.
Mr Kim is scheduled to hold talks with South Korean President Moon Jae-in next week and with US President Donald Trump in late May or early June.
The pledge to halt the development of nuclear weapons, initiated by his grandfather, would mean a significant reversal for Mr Kim, 34, who for years has celebrated such weapons as a pillar of his regimes legitimacy and power.
A testing freeze and commitment to close the test site alone would fall short of Washington's demand that Pyongyang completely dismantle all its nuclear weapons and missiles.
But announcing the concessions now, rather than during summit meetings, shows Mr Kim is serious about denuclearisation talks, experts say.
"The northern nuclear test ground of the DPRK will be dismantled to transparently guarantee the discontinuance of the nuclear test," KCNA said after Mr Kim convened a plenary session of the Central Committee of the ruling Worker's Party today.
The North's official name is the Democratic People's Republic of Korea (DPRK).
The Pyunggye-ri site is North Korea's only known nuclear test site. All of its six underground tests were conducted there, including the last and largest in September.
Mr Trump welcomed the statement and said he looked forward to a summit with Mr Kim.
North Korea has agreed to suspend all Nuclear Tests and close up a major test site. This is very good news for North Korea and the World - big progress! Look forward to our Summit.— Donald J. Trump (@realDonaldTrump) April 20, 2018
South Korea said the North's decision signified "meaningful" progress toward denuclearisation of the peninsula and would create favourable conditions for successful meetings with it and with the United States.
China, North Korea's sole major ally, has been frustrated by its defiant development of weapons and welcomed the announcement, saying it would ease tension and promote denuclearisation.
"The Chinese side believes that North Korea's decision will help ameliorate the situation on the peninsula," a foreign ministry spokesman, Lu Kang, said in a statement.
The Russian Foreign Ministry said it welcomed the announcement by North Korea and called on the US and South Korea to reduce their military activity in the region.
- US ready to talk to North Korea without preconditions
- Timeline - US and North Korea nuclear standoff
- North Korea says new UN sanctions an act of war
- North Korea showcases new missiles in parade
Japanese Prime Minister Shinzo Abe also welcomed the North Korean statement but said it must lead to action.
"What's important is that this leads to complete, verifiable denuclearisation. I want to emphasise this," Mr Abe told reporters.
Australia and Britain were also cautious.
The British government said in a statement that Pyongyang's commitment was a positive step and hoped it indicated "an effort to negotiate in good faith".
Australian Foreign Minister Julie Bishop said "verifiable steps" would be needed to ensure testing had indeed been halted.
The European Union's foreign affairs chief Federica Mogherini said North Korea's move was a positive step and called for an "irreversible denuclearisation" of the country.
German Foreign Minister Heiko Maas said North Korea's announcement was a step in the right direction but it must "disclose its complete nuclear and missile programme in a verifiable way".