Kim Jong-un has agreed to shut down one of North Korea’s main missile testing and launch sites, says South Korea’s President Moon Jae-in.
After meeting in Pyongyang, the two leaders “agreed on a way to achieve denuclearisation,” said Mr Moon.
The agreement was described by Mr Kim as a “leap forward” towards military peace on the peninsula.
Mr Kim also said he hoped to “visit Seoul in the near future” – he would be the first North Korean leader to do so.
Summit results: Denuclearisation
The main focus of the summit was the issue of denuclearisation. While the US and North Korea agreed in broad terms earlier this year to work towards that goal, negotiations have stalled.
Pyongyang has now sought to reconfirm its commitment.
Media captionThe war that never officially ended
Mr Moon said Mr Kim had “agreed to permanently close the Tongchang-ri missile engine test site and missile launch facility” and, crucially, that this would be done “in the presence of experts from relevant nations“.
The BBC’s Seoul correspondent Laura Bicker said allowing independent inspectors to see the dismantling of the Tongchang-ri site was “a major step forward”.
She added that satellite images had suggested that Tongchang-ri was “in the process” of being destroyed, but that the declaration would “allow inspectors to verify the process”.
Tongchang-ri has been North Korea’s main satellite launch facility since 2012, according to monitoring group 38 North.
It has also been used for testing engines for North Korean missiles capable of reaching the US.
Read more on North Korea’s missile and nuclear programme
He said Mr Kim had also agreed to shut down the Yongbyon nuclear facility – where North Korea is believed to have produced the material used in its nuclear tests – but only if the US took some reciprocal action. The details of that were not specified.
North Korea blew up its main nuclear testing site at Punggye-ri shortly before Mr Kim’s meeting with US President Donald Trump in June.
“The outcome is a big win for Moon Jae-in, who has managed to extract a series of positive headlines from Kim Jong-un related to denuclearisation,” Ankit Panda, editor of The Diplomat, told the BBC.
“None of the concessions are truly costly to Kim and won’t help move North Korea toward short-term disarmament, but provide a further basis for confidence building on which US-North Korea talks can move forward.”
Summit results: North and South relations
The two countries also made advances on inter-Korean ties, announcing plans to link up their railways, allow more reunions for families separated by war and co-operate on health care.
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Mr Moon invited the North Korean leader to Seoul, suggesting the visit should take place before the end of this year.
They will also seek to co-host the 2032 Summer Olympics.