SEOUL, South Korea — North Korean leader Kim Jong Un has left for China for a four-day trip, the North’s state media reported Tuesday, amid speculation that he may attempt to coordinate his positions with Beijing ahead of his likely summit with President Donald Trump.

The Korean Central News Agency said that Kim departed for China on Monday afternoon with his wife Ri Sol Ju and top officials. It said Kim is visiting China at the invitation of Chinese President Xi Jinping.

The KCNA dispatch came after South Korean media reported late Monday that Kim may be on his way to Beijing aboard a special train for his summit with Xi.

South Korean media reported the train was expected to reach Beijing at about 10 a.m. Tuesday local time. Kim used a very distinctive armored train made especially for him on visits to China last year.

Kim’s trip comes after U.S. and North Korean officials are believed to have met in Vietnam to discuss the location of a second summit between Kim and Trump.

Kim visited China three times last year as he was engaged in a flurry of diplomacy with the United States and South Korea since he abruptly entered talks about the fate of his advancing nuclear arsenal. Nuclear diplomacy has reported little progress since Kim met Trump for a summit in Singapore last June.

China is North Korea’s most important trading partner and a key buffer against pressure from Washington.

Tuesday is also Kim Jong Un’s birthday.

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