North Korea's leader Kim Jong Un made his fourth visit to China on Tuesday, believed to be his 36th birthday, at the invitation of President Xi Jinping, as the stalemate in Pyongyang's denuclearization negotiations with the United States continues.During his stay, Kim is likely to meet with Xi and attempt to obtain backing from China -- North Korea's main economic and political supporter -- in envisioned fresh talks with U.S. President Donald Trump, expected to take place early this year.[KNS/Kyodo]The state-run Korean Central News Agency said that Kim left Pyongyang on a special train on M…READ FULL ARTICLE