As China's trade war with the United States shows no sign of abating, Chinese President Xi Jinping arrived in North Korea on June 20 for a two-day state visit -- the first by a Chinese premier in 14 years. Xi's visit with North Korean supreme leader Kim Jong Un in Pyongyang comes a week before he is scheduled to meet with U.S. President Donald Trump at the June 28-29 G-20 summit in Osaka, Japan. The crucial G-20 meeting will provide an opportunity for the world leaders to gauge a potential cease-fire in the U.S.-China trade war. The timing of Xi's visit to North Korea is key, however, because it also coincides with a prolonged impasse in nuclear talks between Pyongyang and Washington following the breakdown of Kim's February summit with Trump in Hanoi, Vietnam -- something Xi may seek to leverage in trade negotiations....