Kim Jong-un and Xi Jinping's meeting
North Korea's supreme leader Kim Jong-un secretly met with China's paramount leader Xi Jinping on March 25–28 2018. Chinese leader Xi Jinping made a classified invitation to North Korea leader Kim Jong-un to visit China. North Korea leader Kim Jong-un visited Beijing using his bullet proof train to travel to the three-day meeting. It is his first known out-of-country diplomatic trip since taking power.
The secret China-North Korea meeting was organised by the invitation from Xi Jinping, General Secretary of the Communist Party of China (de facto paramount leader). During the meeting between two one-party state leaders, Kim Jong-un officially invited Xi Jinping to Pyongyang at a time convenient for him, and Xi accepted the invitation.  During the confidential summit schedule, Xi Jinping presented and explained the list of the present to Kim Jong-un. Kim Jong-un also prepared several gifts for Xi Jinping and described the details to Xi Jinping.  Xi Jinping urged Kim Jong-un to strengthen its strategic and diplomatic future partnership between China and North Korea. Kim Jong-un stressed to Xi Jinping that North Korea and China are long communist countries and that there are many ways to cooperate in various aspects in the future. 
Regarding North Korea nuclear crisis with a diplomatic solution and Beijing's issue with US trade war, Two leaders meeting might be substantial leverage for answering to a puzzle of resolution to both two long-lasting communist countries.
As regards Chinese state news agency, Xinhua, quoted Kim's statement "The issue of denuclearization of the Korean Peninsula is resolved, and South Korea and the United States respond to our efforts with goodwill, create an atmosphere of peace and stability while taking progressive and synchronous measures for the realization of peace. " President Trump’s new national security advisor: John Bolton would not adopt the unreasonable solution - examples: sheer costs for North Korean denuclearization (e.g., withdrawal of U.S. troops from the peninsula or mutual denuclearization for both DPRK and USA) after Kim-Xi summit. 
Director of defense studies at the Center for the National Interest USA: Mr Harry J. Kazianis consider that "the purpose of DPRK-China summit" it would argue that Kim Jung-un wanted to meet President Xi to measure Beijing’s tolerance for North Korea’s strategy or potential solution for a summit with USA President Trump. It is even possible that Kim might have been consulting with his Chinese mentor to help him get out of the risky summit entirely because of the insecurity of denuclearization. 
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