During the campaign, Mr. Trump had a simplistic view of North Korea as a client state of China that could be brought to heel at Beijing's whim. After a tutorial at Mar-a-Lago from Chinese President Xi Jinping, President Trump has come to the conclusion that "it's not so easy." In an interview with the Wall Street Journal last week, he added, "I felt pretty strongly that they had a tremendous power [over] North Korea. ... But it's not what you would think." The next day, he tweeted "I have great confidence that China will properly deal with North Korea. If they are unable to do so, the U.S., with its allies, will! U.S.A." Then on Sunday he tweeted "Why would I call China a currency manipulator when they are working with us on the North Korean problem? We will see what happens!"