Hours after an armoured train departed Beijing for Pyongyang on Tuesday, the identity of the mysterious VIP who had visited China under tight security was revealed as Kim Jong Un, the North Korean dictator who was making his first foreign trip since becoming leader in 2011.

The not-quite secret visit came as Mr Kim and President Donald Trump prepare for a possible summit after months of tensions over the nuclear crisis on the Korean peninsula. While China did not announce their guest in advance, it did not hide the fact that an important dignitary was in Beijing by providing Mr Kim with a high-profile motorcade normally reserved for only the most important visitors.

Although China did not release any details as Mr Kim was returning to North Korea on Tuesday after his two-day stay, it was assumed he had met Chinese president Xi Jinping given the protocol surrounding the visits of Communist party leaders to China.