Mr Kim will likely spend over 20 hours on the slow-moving locomotive, which has a restaurant serving French wines and lobster dishes, as is a long-standing tradition among North Korean leaders.

As a result of its heavy armor, the train rattles along at about 50km/h (31mph).

London’s high-speed rail runs at about 200 km/h, while Japan’s Shinkansen bullet trains reach 320 km/h.

It also takes into account the sometimes archaic rail network in the North.

Taeyangho, the Korean word for the sun, is a symbol of North Korea’s founder Kim Il Sung. A tradition of long-distance travel by train was established by Kim Il Sung, Kim Jong Un’s grandfather, who took his own train to Vietnam and Eastern Europe.

Security agents scan routes and upcoming stations for bombs and other threats on these luxurious trains.

As a result of his fear of flying, Kim Jong Il, Kim Jong Un’s father, travelled by train from 1994 until his death in 2011.

A meeting between Kim Jong Il and Vladimir Putin in 2001 took Kim Jong Il ten days to reach Moscow.