Why is Chinese President Xi Jinping visiting North Korea now? - Al Jazeera

Why is Chinese President Xi Jinping visiting North Korea now?  Al JazeeraKim Jong Un's sister vows North Korea will never give up nuclear weapons  Sky NewsWith China's Xi in North Korea, Kim to project confidence, defiance  ReutersChina’s Xi Jinping to make rare trip to North Korea next week  CNNChina's Xi Jinping to meet Kim Jong Un in rare visit to North Korea  BBC