The last summit between leaders of the two Koreas occurred in 2007 when South Korean President Roh Moo Hyun and Kim Jong-il met in Pyongyang, North Korea's capital.
It was the US that appeared to be the one left in the cold, especially after the sister of the North Korean dictator extended an invitation from her brother for Moon to visit the North.
One swimming champ who won gold in Barcelona in 1992 said on Twitter she will be sleeping in her team United States of America beenie to prepare for the games to kick off. "Kim Jong-un has no intention of giving up his nuclear weapons", said Cheon Seong-whun, a former presidential secretary for security strategy and now a visiting research fellow at the Asan Institute for Policy Studies in Seoul.
"We are not going to reveal the source", said Sung Baik-you, spokesman for the Games' local organisers.
Moon has said he hopes to be able to set the conditions to hold a summit between the two leaders in the North.
A handful of sports had previously begun qualifying rounds or actual competition, but the Opening Ceremony serves as an occasion for athletes to gather and celebrate their similarities, rather than their differences and rivalries.
At a Games rife with political overtones, US Vice-President Mike Pence was watching nearby as the first North Korean athlete competed - and flopped - on Saturday.
"The vice president is grateful that President Moon reaffirmed his strong commitment to the global maximum pressure campaign and for his support for continued sanctions", Pence spokeswoman Alyssa Farah said when asked about the developments. That's also significant: Top South Korean and North Korean officials rarely interact with one another.
But the previous agreements broke down as North Korea pressed ahead with its nuclear program.
Camera flashes; mobs of reporters: Through it all, Kim has maintained a placid smile - and despite Pence's stated intention to reinforce North Korea's isolation during his Olympic visit, the sister of the repressive regime's leader seems to have spent at least as much time with Moon as Pence did.
The spokesman says Moon also called for a quick resumption of dialogue between the United States and North Korea.
WINNER. In this file photo, Lim Hyo-Jun of South Korea celebrates victory during the men's 5000m relay final event at the ISU World Cup Short Track Speed Skating in Seoul on November 19, 2017.