One of North Korean leader Kim Jong-un's most senior officials is thought to be travelling to the US, as preparations for a possible summit gather pace.
South Korean news agency Yonhap said Gen Kim Yong-chol was due to arrive in the US on Wednesday, via Beijing.
This could be part of preparation for a proposed meeting between Mr Kim and President Donald Trump.
The meeting was thrown into doubt after Mr Trump pulled out last week.
But both sides have been working to get the summit - scheduled for 12 June in Singapore - back on track.
It would be the first time a North Korean leader has met a sitting US president.
Gen Kim was scheduled to fly to New York on Wednesday, after speaking with Chinese officials in Beijing, Yonhap reported, citing diplomatic sources.
He would be the most high-profile North Korean official to visit the US since 2000.
The apparent introduction of Gen Kim to negotiations would be significant, as it would underline North Korea's desire to ensure the talks go ahead.
A former spy chief, he has been part of recent high-profile diplomatic overtures by the North.