He controls a million-strong army and runs a nuclear weapons programme but for years Kim Jong Un has ruled with a nagging sense of fear. The young North Korean dictator, some argue, was afraid to leave his isolated, impoverished nation in case his generals launched a coup or foreign forces used the opportunity to bring his brutal reign to an abrupt end.

Such notions were shattered this week as a private armoured train trundled 20 hours from Pyongyang to Beijing for Mr Kim’s first trip abroad as paramount leader of North Korea.

The visit, initially shrouded in secrecy with the Chinese capital on lockdown, was seen by experts as an attempt to mend Pyongyang’s frayed ties with Beijing — its principal backer — ahead of a possible summit between Mr Kim and US president Donald Trump in May. But to others it signalled something more: the dictator’s growing confidence in his hold on power — a position that he has for years meticulously strengthened through a series of political, economic and military policies that are becoming synonymous with his reign.