After Seoul, the South Korean delegation will visit the United States to brief USA officials on the outcomes of their trip to North Korea.
It is a challenging task - in defiance of United Nations sanctions, the isolated and impoverished North previous year staged its most powerful nuclear test and test-fired several missiles, some of them capable of reaching the USA mainland. Six-party talks, grouping the two Koreas, Russia, China, Japan and the U.S., and offering the North security and economic benefits in exchange for denuclearisation, broke down nearly a decade ago. Or, so South Korea says. They agreed to have their first phone call before the summit in April.
North Korea has yet to confirm details of the announcements from Seoul that appeared to open the door to dialogue between Washington and Pyongyang after a year of escalating threats by Trump and North Korean leader Kim Jong Un, and escalating fears of war.
In November, he declared the programme complete after successfully testing an intercontinental ballistic missile that arms control experts believe could reach any United States city. In a speech to the UN General Assembly he threatened to "totally destroy" the North if it continued to be a regional security threat.
The Koreas are to hold working-level talks ahead of the summit between Kim and liberal South Korean President Moon Jae-in. "All efforts in the past have failed and it simply bought North Korea time to achieve what they want to achieve".
The Winter Olympics provided "a good atmosphere of reconciliation, unity, and dialogue between the North and the South", Jong-un stated.
Kim can be seen in a North Korean TV video smiling and laughing, proposing a toast at the dinner reception, and waving as two limousines carrying the South Korean delegates left the main building of the ruling Workers' Party.
He said the North had promised not to use conventional or nuclear weapons against South Korea.
The North is subject to multiple rounds of UN Security Council sanctions over its atomic and ballistic missile programmes, and has long insisted that its "treasured sword" is not up for negotiation. It was the first time that Kim's wife Ri met South Korean officials since she became the first lady of the reclusive state.
As recently as Saturday, North Korea said the country wouldn't accept U.S. preconditions. This commitment comes even as the USA and South Korean militaries prepare to start huge annual drills that North Korea considers preparation for an invasion and that typically lead to a sudden increase in tensions on the peninsula.