Kim is visiting China with his wife Ri Sol-ju, state media report/EPA
North Korean leader Kim Jong-un is visiting China at the invitation of President Xi Jinping, North Korean and Chinese state media have confirmed.
Mr Kim will be in China until 10 January with his wife Ri Sol-ju, said the reports, according to BBC.
The visit comes amid reports that negotiations are under way for a second summit between Mr Kim and US President Donald Trump.
The two met last June, the first such meeting for a sitting US president.
Speculation had grown on Monday that Mr Kim was possibly making his way to China on board his armoured train.
The visit, during which he is being accompanied by several leading North Korean officials, is his fourth to China in less than a year.
Tuesday is also reportedly Mr Kim's 35th birthday, though his date of birth has never been confirmed by Pyongyang.
China is an important diplomatic ally for North Korea, and one of its main sources of trade and aid.
"[Mr] Kim is eager to remind the Trump administration that he does have diplomatic and economic options besides what Washington and Seoul can offer," Harry J Kazianis, Director of Defense Studies at the Centre for the National Interest told Reuters.