As announced by both North Korean and Chinese state media
Xi is to visit Pyongyang at the invitation of North Korean leader, Kim Jong Un. In case you need a refresher, the two leaders had also met earlier this year on 7-10 January. It was one of those secret meetings in which Kim took the time to head over to Beijing.
It'll be interesting this time around though with both sides having seen relations with the US sour recently, unlike what sentiment was at the time in January. I'm pretty sure that'll be a common ground they both can land on during their conversation.
