President Trump assures Americans regularly that he has a great relationship with an array of world figures, among them Xi Jinping of China and Kim Jong-un of North Korea. It's comforting to hear. It would be more gratifying, though, to see these relationships bear fruit. Try as he might, the president has been stymied in his efforts to seal crucial deals with his Asian counterparts. Americans may be subject to creeping doubts, but there is no substitute for persistence.