SEOUL (Reuters) - North Korean leader Kim Jong Un is on his way to China for his fourth summit with China’s Xi Jinping, South Korean media said on Monday.

South Korea’s Hankyoreh newspaper, citing an unidentified source with close knowledge of North Korea-China affairs, reported that Kim was traveling to Beijing late on Monday to meet with Xi.

South Korea’s Yonhap news agency, citing an unspecified source familiar with North Korea issues, said a North Korean train possibly carrying a “high-level” official had crossed the border into China.

The source told Yonhap it had not been confirmed whether a senior official was on board, but that dozens of security vehicles and officials had blocked the roads around a station in the Chinese border city of Dandong as the train passed.

Last yearKim traveled to China three times to meet with Xi, before and after Kim held other summits with U.S. President Donald Trump and South Korean President Moon Jae-in.

Kim is expected to meet again with both the U.S. and South Korean presidents in the near future, and another visit to China has been seen as a possible move before those summits.

Earlier on Monday the South Korean newspaper Munhwa Ilbo reported that U.S. State Department officials recently met multiple times with North Korean counterparts in Hanoi and discussed planning a second summit between Trump and Kim, fuelling speculation that Vietnam could host the event.

The U.S. State Department and White House declined to comment on the Munhwa Ilbo report and the State Department referred queries about Kim’s reported China visit to