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 but they tried to avoid directly facing each other, Yonhap news agency reports.
Meanwhile South Korean President Moon Jae-in has shaken hands with North Korean leader Kim Jong-un’s sister at the Winter Olympics opening ceremony.
The Games are taking place amid tension over North Korea’s nuclear programme.
Mr Pence has brought to South Korea as a guest Fred Warmbier, the father of a young American who died after being released from prison in North Korea.
Meanwhile on Thursday North Korea held a military parade that had been scheduled for April but was brought forward.