The old-fashioned train has become a symbol of Kim’s dynasty and his secluded nation. It has also long been the subject of intrigue, carrying generations of the Kim family across the country and on rare international trips.

North Korean state media Rodong Sinmun confirmed early Tuesday that Kim’s train had crossed the border into China, with photos of the leader smiling on board the train, sitting at a wooden table with a North Korean flag behind him. He’s accompanied by senior officials including Foreign Minister Choe Son Hui, according to the country’s foreign ministry.

Kim’s father and predecessor, Kim Jong Il, was reportedly averse to flying and relied heavily on the train, according to Reuters.

In one instance in 2002, Russian state media showed images of the train – green with yellow striping – when Kim Jong Il visited Russia during a brief period of relaxed sanctions that allowed greater engagement with the outside world.

Both Kim’s father and grandfather reportedly hosted lavish dinners abroad. One account published in 2002 by Russian official Konstantin Pulikovsky claimed that the train carried cases of Bordeaux and Beaujolais wine from Paris, and that passengers feasted on live lobster and pork barbecue.

But that brief period of openness and luxury ended quickly, with international sanctions clamping back down in 2003. Though very little information from the isolated nation reaches the outside world now, reports indicate severe impoverishment and malnourishment throughout much of the country.

The train is also famously slow-moving and tight on security. It’s so heavily armoured that it travels at an average speed of 60 kilometres an hour, according to a 2009 report in South Korean newspaper Chosun Ilbo.

It contained conference rooms, an audience chamber and bedrooms and featured satellite phone connections and flat screen televisions, the paper reported at the time. In Kim Jong Il’s time, some 20 stations were built for the family train, the paper said.

Kim has used this train on several trips abroad, though he has also previously travelled by plane and private jet.

Kim rode the train during his last international visit – a 2023 trip to Russia’s far east to meet with his counterpart Vladimir Putin. Photos released by state media at the time offered a glimpse into the locomotive, showing polished wooden floors and an ornately decorated white doorway.

State media footage released in 2022 showed Kim working in his office on board the train, and also relaxing on board while smoking a cigarette in a short-sleeved shirt, according to South Korean news agency Yonhap.

And during a 2018 trip when Kim met Chinese leader Xi Jinping, footage by North Korean state media showed Chinese officials boarding the train to greet Kim. The delegations held talks on board, sitting on two rows of pink couches, photos showed.

Besides international travel, the train has also been featured in state propaganda, with the Kim family going on long train journeys to meet ordinary North Koreans, Reuters reported.

A life-sized model of one of the train’s carriages is displayed in a mausoleum outside the North Korean capital Pyongyang, where the remains of Kim’s father and grandfather are kept.