North Korean leader Kim Jong Un’s fifth meeting with Chinese President Xi Jinping continues his ambitious diplomatic outreach that has included summits with the leaders of the United States, South Korea and Russia in the past year and a half. Experts say Kim is attempting to form a united front with North Korea’s main ally China to strengthen his leverage in the stalled nuclear negotiations with the United States. Some key developments in Kim’s diplomacy: ___ Jan. 1, 2018: Kim in his annual New Year’s address calls for improved relations with South Korea and offers to send a delegation to the Winter Olympics. February 2018: Hundreds of North Koreans attend the Pyeongchang Games, including Kim’s sister, who conveys her brother’s desire for a summit with South Korean President Moon Jae-in. March 7, 2018: A South Korean envoy returns from visiting Pyongyang and says Kim is willing to discuss his nuclear arsenal with Washington. Days later, President Donald Trump accepts Kim’s invitation to meet. March 27, 2018: Kim makes a surprise visit to Beijing to meet with Xi. April 21, 2018: North Korea says it has suspended nuclear and long-range missile tests and is shifting its focus to improving its economy….