The leaders of North and South Korea are due to meet at a summit of the two countries next month, Seoul’s envoy has said after a rare trip to Pyongyang.
N Korea’s Kim Jong-un also said he was willing to talk to the US about getting rid of nuclear weapons, the envoy said.
There have been previous programmes to halt the North’s nuclear ambitions, but it has failed to keep its promises.
It will be the first meeting between the leaders of the two countries for more than a decade.
The two men will meet on the heavily fortified border next month, at the truce village of Panmunjom. The two countries also agreed to open a hotline between the leaders.
On their return from Pyongyang, South Korean officials said Kim Jong-un told them he was now willing to talk about getting rid of the North’s nuclear weapons, if he felt that the regime’s security could be guaranteed.
Mr Kim also said there would be no missile tests while diplomacy continued.
This is a huge turnaround for North Korea’s young leader, the BBC’s Laura Bicker reports from Seoul.
The United States had said talks with North Korea would only go ahead if it was willing to discuss denuclearisation.
The US has said it is “cautiously optimistic” about improving North-South contacts, but ruled out formal talks with Pyongyang unless it was ready to give up its nuclear weapons.
Throughout the Olympics, the US maintained that North Korean gestures of rapprochement would carry little weight without such a commitment – particularly following last year’s nuclear and missile tests carried out by the North.
South Korean officials had dinner with the normally reclusive leader on Monday. Among the delegation were intelligence chief Suh Hoon and National Security Adviser Chung Eui-yong.
They were the first officials from Seoul to meet Mr Kim since he came to power. They returned to Seoul on Tuesday morning, Yonhap news agency said.
The trip was part of a wave of rapprochement moves surrounding last month’s Winter Olympics.
Throughout the Olympics, the US maintained that North Korean gestures of rapprochement would carry little weight without commitment to give up nuclear weapons.
The South Korean delegation is expected to visit Washington later this week to brief US officials on their talks in the North.
Kim Jong-un has met very few foreign officials since he became leader in 2011 and the last time envoys from the South visited Pyongyang was in 2007.
Two previous summits were held in 2000 and 2007, under South Korean presidents Kim Dae-jung and Roh Moo-hyun who met Kim’s father, Kim Jong-il.
So the sight of a southern delegation smiling, shaking hands and sitting down for dinner with him is significant.
They were aiming to capitalise on the reduced tensions after the Games, which saw the Koreas march together under a single flag.
The hope is that future formal talks will break the diplomatic standoff between the US and North Korea and persuade North Korea to abandon its nuclear weapons, something it has fiercely resisted despite ever-increasing punitive sanctions.
The North’s KCNA news agency said Mr Kim had “warmly welcomed” the delegates and held an “openhearted talk” with them.
They passed on a letter from South Korean President Moon Jae-in in which he invited Mr Kim to attend further talks.
KCNA said Mr Kim had “exchanged views and made a satisfactory agreement” on the letter and gave orders for it to be acted on.
The dinner, which lasted four hours, also featured Ri Sol-ju, Mr Kim’s wife who rarely appears at official events, and his sister Kim Yo-jong, who was part of a North Korean delegation to the Pyeongchang Olympics.
The South’s response to the apparently cordial meeting is likely to remain muted until the delegates return to Seoul.
Officials have stressed the talks were only preliminary, but the parties had “somewhat shared” views on some issues.
When asked whether nuclear disarmament had been discussed, a senior officials from Mr Moon’s office said “I assume so”, the Yonhap news agency reports.