North Korea's head of state will go to Pyeongchang this week for the Winter Olympics, the most senior official to ever visit South Korea.
North Korea confirmed Kim Yong-nam's attendance at the opening ceremony, set for Friday.
Both Koreas will march under one flag at the opening ceremony.
Although this signals a thaw in relations between the Koreas, experts say it is unlikely to have any impact on the North's nuclear ambitions.
Mr Kim will be in the South for a three-day visit and will lead a 22-member delegation.
Who is Kim Yong-nam?
The 90-year-old Kim Yong-nam has seen the rule of all three North Korean leaders in his career.
He is the ceremonial head of state who receives credentials from foreign diplomats in Pyongyang. As such, he is usually responsible for sending condolences or congratulatory messages to foreign leaders.
He has been the president of North Korea's rubber-stamp parliament, the Supreme People's Assembly, since 1998.
Unlike the current leader Kim Jong-un, Kim Yong-nam has travelled abroad on official visits. In August 2017, he travelled to Iran to attend President Hassan Rouhani's inauguration ceremony for his second term in office.
He also attended the opening ceremony of the Winter Olympic Games in Sochi, Russia in 2014.
Mr Kim is said to be a loyal follower of the top leadership. "As Kim is known to be acting and speaking under the country's guidance, he makes no mistakes. That's why he could keep his high-level post in a country where political purges are common," South Korea's Yonhap news agency quoted one North Korean defector as saying.
What is the significance of his visit?
An unnamed official from the South's presidential Blue House told the BBC that they believed Mr Kim's visit reflected a willingness on the part of North Korea to improve inter-Korean relations, and demonstrated the North's sincerity.
Seoul has said it will seek high-level talks with the North Korean delegation during the visit, Yonhap reported.
Mr Kim's attendance at the opening ceremony will also put him in the company of US Vice President Mike Pence, at a point of high tension with Washington over the North's nuclear ambitions.
In another development on Sunday, the Washington Post reported that Fred Warmbier, whose son Otto Warmbier was jailed by North Korea and died days after returning to the US, would attend the opening ceremony as a guest of Mr Pence.
Mr Warmbier and his wife, Cindy, were guests of US President Donald Trump at last week's State of the Union address.
How has the North been involved in the Games so far?
North Korea on Monday proposed sending an art troupe to the Games by ferry, a move that would require an exemption from bilateral sanctions.
Pyongyang proposed that its delegation use the Mangyongbong 92, a ferry that usually operates between North Korea and Russia, for transportation and as accommodation for the group, according to the South's unification ministry.
All North Korean ships have been banned from entering South Korean ports since 2010.
"We're seeking to apply an exemption... to support a successful hosting of the Olympics," South Korean ministry spokesman Baik Tae-hyun told a press conference.
On Sunday, the united Korean women's ice hockey team played its first match, but lost the friendly against Sweden 1-3.
Sunday's outing was the first and only practice match for the newly minted Korean squad.
As well as the ice hockey players, North Korean athletes will compete in skiing and figure skating events. It is also sending hundreds of delegates, cheerleaders and performers.
What are relations like between North and South Korea?
North Korea currently faces growing international pressure and sanctions over its nuclear and missile programmes after it conducted a series of missile tests designed to demonstrate its nuclear capability.
North Korea's participation in the Olympics, which run from 9 to 25 February, was an unexpected warming of ties.
It came after the hereditary leader Kim Jong-un extended an olive branch to the South in a New Year message, saying he was open to dialogue and could send a team to the Games.
However, there have already been some signs of the tensions that underpins this relationship.
Earlier this week it emerged that the North had scheduled a large-scale military parade for 8 February, the day before the Winter Olympics commences.
Amid negative headlines, North Korea said no-one had the right to take issue with its plans and promptly cancelled a cultural event it was to hold jointly with the South.
Meanwhile, although Seoul and Washington have agreed to delay the annual big joint military exercises which always enrage the North, they will still go ahead at the end of the Paralympics.