It's been a roller-coaster ride. On May 24, U.S. President Donald Trump canceled his summit with North Korean leader Kim Jong Un citing the latter's "open hostility." Hours later, Kim had his diplomat express his willingness to talk, had a surprise meeting with South Korean President Moon Jae-in, and then sent one of his closest aides, Kim Yong Chol, to New York and Washington to deliver his personal letter to Trump in an extraordinarily big envelop. Trump accepted it as a positive sign and decided to meet Kim as originally scheduled in Singapore on June 12.

There is a big difference before and after this roller-coaster ride. Trump no longer expects an immediate denuclearization of North Korea. He says the June 12 meeting will be about building a relationship, indicating that the denuclearization takes time, and does not want to use the term "maximum pressure" as he and Kim go along. In some sense, Trump has come down to a realistic startling line. The denuclearization process is complex, time-consuming and expensive, therefore needs to take "gradual and synchronous measures" as Kim expects. Even in the case of Libya, which never succeeded in developing nuclear arsenal, it took almost two years from initial negotiation to the essential denuclearization. The denuclearization of an actual nuclear weapon-state like North Korea cannot be completed in Trump's first term.

But Trump has missed opportunities to take a position of strength. Trump seems to think he has given up nothing for having the first meeting between a sitting president of the United States and a North Korean leader. He may even think he got the three Americans back for free. But he should not have thanked Kim for freeing them. Instead Trump should have demanded an apology and compensation for the fate of Otto Warmbier, who last year was released in a state of unconsciousness and soon died. Trump could demand the settlement of North Korea's past breaking of promises, in addition to the pledge for denuclearization, as a condition for holding the summit, but he didn't. He didn't even raise human rights issues with Kim Yong Chol.