The North's invitation was hand delivered by Kim Jong-un's sister, Kim Yo-jong, who attended the opening ceremony of the Pyeongchang Winter Olympics in the South, officials say. The divided Koreas are playing under the unification flag in the Games.
North Korean leader Kim Jong-un has formally invited his South Korean counterpart Moon Jae-in for a visit to Pyongyang in a hand delivered invitation carried by his sister Kim Yo-jong, Seoul said on Saturday.
Yo-jong arrived in the South on Friday and attended the opening ceremony of the Pyeongchang Winter Olympics.
It's the first time since 1950 that a member of the Kim Jong family has set foot on South Korean soil.
"The letter from Kim Jong-un contains his willingness to improve the inter-Korea relationship. Then she [Kim Yo-jong] verbally delivered Chairman Kim Jong-un's invitation to Pyongyang at convenient time, saying he is willing to meet President Moon Jae-in at the earliest date," said Kim Eui-kyeom, spokesperson of South Korea's Presidential Blue House.
The divided nations are marching and playing under the Korean unification flag in the ongoing Winter Olympics.
Yo-jong's visit, however, sparked protests down the road from Presidential Blue House.
"We are very upset and we disagree with the Pyeongchang Olympics, which is prepared by SouthKoreans, but has now turned into Pyongyang Olympics. We are here to protest against it," said Choi Tae-sun, a 63-year-old protester.
Another elderly protester, Joo Ok-soon said, "I think Moon Jae-in's government fell for Kim Jong-un's trickery, which is using Kim Yo-jong's trip as a shield to hide its nuclear weapons."
TRT World's Staci Bivens has more on the warming up of the two Koreas.