"The inter-Korean relations should be mended by the parties concerned at any cost", Moon was quoted by the agency as adding. "Moon has always wanted an early summit and Pyongyang has its own political reasons for reviving inter-Korean cooperation". She later gave that folder to Moon, and Moon's office said it was a personal letter from her brother.
However, South Korea's main opposition party warned that any talks between the two Koreas where the scrapping of North Korea's nuclear program was not a precondition would only "benefit the enemy".
Washington insists that Pyongyang - which is under multiple sets of United Nations Security Council sanctions - must take concrete steps toward denuclearization before any negotiations can take place.
If the envisioned Moon-Kim summit were to be held, the North Korean leader would find himself in an advantageous position.
With a smile, a handshake and a warm message in South Korea's presidential guest book, Kim Yo Jong has struck a chord with the public just one day into the PyeongChang Games.
"Her being here is not that bad, but I feel North Korea has shown up to the Olympics without paying", said Yoon Jun-young, 23, indicating that the nation hasn't made any political concessions to mirror its participation on the global sporting stage.
She's been known to act as an advance-team leader, inspecting sites before official visits and taking on administrative duties, analysts said.
"I am very confident, as President Trump is, that President Moon will continue to stand strongly with us in our extreme-pressure campaign", Pence told NBC in an interview on Friday, maintaining all options were open to deal with the crisis.
U.S. Vice President Mike Pence's efforts to keep North Korea from stealing the show at the Winter Olympics proved short-lived, drowned out by images of the two Koreas marching and competing as one.
White House officials stressed that Pence had applauded only for the American team, but some observers said the vice president's refusal to stand could be seen as both divisive and disrespectful to the hosts.
But Pyongyang's nuclear programme will hang over any attempts to bring the countries closer together.
Moon Jae-in must now walk a fine diplomatic line as he tries to encourage North Korea's new interest in dialogue without straying too far from the "maximum pressure" approach championed by the United States, South Korea's military ally.
Just before the opening ceremony, Kim Yong Nam attended a dinner for visiting foreign dignitaries hosted by Moon. They also made plans to attend a concert together on Sunday, to see a North Korean orchestra perform in Seoul.
South Korean President Moon Jae-in received an invitation to visit the North during the most significant diplomatic encounter between the rivals in years.
While some concessions - including an at least partial scaling back of the USA -led pressure campaign - could be a bridge too far for Washington, any failure of the current inter-Korean rapprochement would also likely be seen as a win for Pyongyang.
If the dictator believes his sister's press clippings from CNN and the Washington Post - if he thinks his sister has won a gold medal for "diplomatic dance" and that she has added to the distance between South Korea and the USA - it could make him more reckless.
Except that Kim Jong Un and his team, by some accounts, pay considerable attention to how the USA perceives them.
"It means he doesn't necessarily have to hold to the hard-line comments he's made in the past", Oba said. -South Korea alliance were evident immediately after the announcement.