A special adviser to President Moon Jae-in says he believes North Korea-U.S. talks were postponed this week because dialogue on sanctions is not going smoothly. 

Moon Chung-in told reporters in Beijing Thursday that the North probably called off the meeting because Washington has failed to ease sanctions in response to North Korean denuclearization steps.

U.S. Secretary of State Mike Pompeo had been scheduled to meet North Korea's Kim Yong-chol in New York Thursday.

The presidential adviser did say it was possible the two might meet before the end of the year, and was also upbeat about the possibility of a visit by North Korean leader Kim Jong-un to Seoul during 2018.