Train possibly belonging to North Korean leader spotted in resort town

Reporting from inside North Korea is notoriously difficult because of tight controls on information.

A Trump administration official said continuing days of North Korean media silence on Kim's whereabouts had heightened concerns about his condition, and that information remained scant from a country U.S. intelligence has long regarded as a "black box."

The U.S. State Department did not immediately respond to questions about the situation on Saturday.

Daily NK, a Seoul-based website that reports on North Korea, cited one unnamed source in North Korea on Monday as saying that Kim had undergone medical treatment in the resort county of Hyangsan north of the capital Pyongyang.

It said that Kim was recovering after undergoing a cardiovascular procedure on April 12.

Since then, multiple South Korean media reports have cited unnamed sources this week saying that Kim might be staying in the Wonsan area.

On Friday, local news agency Newsis cited South Korean intelligence sources as reporting that a special train for Kim's use had been seen in Wonsan, while Kim's private plane remained in Pyongyang.

Newsis reported Kim may be sheltering from COVID-19, the respiratory disease caused by the novel coronavirus.

Kim, believed to be 36, has disappeared from coverage in North Korean state media before. In 2014, he vanished for more than a month and North Korean state TV later showed him walking with a limp.

Speculation about his health has been fanned by his heavy smoking, apparent weight gain since taking power and family history of cardiovascular problems.