North Korea's leader Kim Jong-un has announced Pyongyang will carry out no more nuclear or intercontinental ballistic missile tests and will shut down its atomic test site, the North's state media reported on Saturday.
The declaration, long sought by the US, will be seen as a crucial step ahead of key leaders summits in the coming weeks.
It comes less than a week before Kim meets South Korean leader Moon Jae-in for a summit in the Demilitarised Zone that divides the peninsula, and ahead of a much-anticipated encounter with US President Donald Trump.
As the weaponisation of nuclear weapons has been verified, it is not necessary for us to conduct any more nuclear tests or test launches of mid- and long range missiles or ICBMs," Kim told a ruling party meeting.
"The northern nuclear test site has completed its mission," he added at the gathering of the central committee of the Workers' Party, according to the official KCNA news agency.
The North's decisions were made in a meeting of the ruling party's full Central Committee which had convened to discuss a "new stage" of policies.
Pyongyang has made rapid technological progress in its weapons programmes under Kim, which has seen it subjected to increasingly strict sanctions by the UN Security Council, US, EU, South Korea and others.
Last year it carried out its sixth nuclear test, by far its most powerful to date, and launched missiles capable of reaching mainland United States.
Analysts said the move announcement was significant but noted the regime was not ruling out future tests.
"The precise language here is important," said Vipin Narang, a nonproliferation expert at MIT.
"Closing the testing site doesn't preclude atmospheric nuclear tests for example (or other sites). And missile tests could still be conducted under the guise of space launch vehicles."