Kim Yong Chol, a close aide of North Korean leader Kim Jong Un, left Thursday for Washington by air from Beijing to lay the groundwork for a second summit between the two countries, as their denuclearization negotiations remain at an impasse.The North Korean senior official boarded a Washington-bound flight of United Airlines, a major U.S. carrier, after having arrived from Pyongyang earlier in the day. He is reportedly carrying a letter from Kim Jong Un to U.S. President Donald Trump.The vice chairman of the Central Committee of the Workers' Party of Korea is likely to hold talks with U.S.…READ FULL ARTICLE