US Vice-President Mike Pence has skipped a dinner at which he was due to share a table with North Korea's ceremonial head of state Kim Yong-nam.
Mr Pence briefly encountered Mr Kim on Friday but they tried to avoid directly facing each other, BBC said citing Yonhap news agency.
Later South Korean President Moon Jae-in shook hands with North Korean leader Kim Jong-un's sister, Kim Yo-jong, at the Winter Olympics opening ceremony.
The Games are taking place amid tension over North Korea's nuclear programme.