North Korean leader Kim Jong-un, who has disappeared from public view recently, might have been spending time at his luxury seaside compound, satellite images suggest.
Rumours about Mr Kim's health have been circulating since his unprecedented absence from April 15 celebrations to mark the birthday of his late grandfather and North Korea's founder, Kim Il-sung.
However, websites monitoring North Korea say commercial satellite imagery shows boats often used by Mr Kim had made movements that suggested he or his entourage may be in the coastal resort of Wonsan.
Officials in South Korea and the US say it is plausible Mr Kim may be staying there, possibly to avoid exposure to coronavirus, and have expressed scepticism about media reports that he had some kind of serious illness.
They caution, however, that Mr Kim's health and location are closely guarded secrets and reliable information is difficult to obtain in North Korea.
The last time official media in North Korea reported on Mr Kim's whereabouts was when he presided over a meeting on April 11, but there have been near-daily reports of him sending letters and diplomatic messages.
Mr Kim's compound in Wonsan, on the country's east coast, is dotted with guest villas and serviced by a private beach, basketball court, and private train station, according to experts and satellite imagery.
An airstrip was bulldozed last year to build a horse-riding track, while a boathouse nearby shelters Mr Kim's Princess 95 luxury yacht.
"It's one of his favourite houses," said Michael Madden, a North Korea leadership expert at the US-based Stimson Centre, who has compared Mr Kim's affinity for Wonsan to Donald Trump's for Mar-a-Lago in Palm Beach, Florida.
Mr Madden said Mr Kim is believed to have about 13 significant compounds around the country, though he appears to only regularly use about half of them.
"All of them are set up to serve as the leader's headquarters, so they are all equipped for him to run the country," he said.
Wonsan is one of the larger and better appointed compounds, but it also has a useful location that allows Mr Kim to easily travel to other areas along the coast, or return quickly to Pyongyang in his private train or along a special highway designated for use only by the Kim family or top officials.
Wonsan also holds symbolic power for the Kim dynasty: It was there that Kim Il-sung, who helped found North Korea at the end of Japanese colonial rule in 1945, first landed with Soviet troops to take over the country.
Wonsan is believed by some experts to be Kim Jong-un's birthplace, partly because he spent his early years at the family's palace there.
Japanese chef Kenji Fujimoto, who worked for the Kims and visited Wonsan, recounted in his memoirs how a young Kim Jong-un rollerbladed, played basketball, rode jetskis and swam in the pool at the compound.
Later, photos showed Mr Kim sipping drinks there with American basketball player Dennis Rodman when the star visited North Korea in 2013.
The Wonsan area has also become emblematic of Mr Kim's strategy for survival based on a combination of economic development, tourism, and nuclear weapons.
He is rebuilding the city of 360,000 people and wants to turn it into a tourist hotspot.
Recently, the project has been delayed, undermined in part by international sanctions over Pyongyang's nuclear and missile programmes, which have restricted its ability to seek foreign investment.
Wonsan has also been the scene of some of Mr Kim's renewed military drills and missile tests, which he resumed amid increasing frustration with a lack of progress in denuclearisation talks with the US and South Korea.