North Korea's leader has called for a "further livening up" of the "warm climate of reconciliation" with the South created by the Winter Olympics.
Kim Jong-un, whose nuclear bomb and missile tests have stoked international tension, praised the South for hosting his state at the games in Pyeongchang.
Kim's apparent Games charm offensive was led by his sister Kim Yo-jong.
South Korean President President Moon Jae-in has meanwhile said the US is open to talking with the North.
He did not elaborate and may have been referring to a remark by US Vice-President Mike Pence on his flight back to Washington from the Games.
"If you want to talk, we'll talk," Mr Pence was quoted as saying by the Washington Post.
While the North's attendance at the Games has been seen as marking a major warming in relations, there have also been concerns that it has allowed it to win a propaganda victory.