Trump initiating a meeting with Kim in May shocked many experts into oblivion. They did know that North Korea had invited to talk to American presidents before, but they did not expect Trump to accept. However, Trump doesn't know that he is supposed to reject. But Trump didn't care. He accepted it because doing so would make him look good. Trump made that decision on the spot as based on his impulsive personality. Trump's impulsive personality created the talks with North Korea because he understaffed the state department, misunderstood the diplomatic process, and let himself be uncontrollable in making rash decisions.
Trump made the state department under-staffed, especially those who have credentials with dealing with North Korea. Just recently, Joseph Yun resigned his position as US Envoy for North Korea. Yun said he retired for personal reasons. However, Reuters reported that he considered retiring due to the constant push for the military option. Chun advocated for diplomacy, as shown by his back channel. Even when the two head of states engaged in a vulgar spat of words, he still kept the channel going, although he admitted that maintaining the channel was difficult. With Chun's expertise gone, then the White House is already in a difficult starting point already. The talks would require more communication between North Korea and the United States, especially between lower-level officials of each countries' foreign ministries.
By understaffing the state department, the Trump administration misunderstood the diplomatic process. Max Fisher said that when preparing for head of states to talk to each other, the lower officials have to do the "dirty work," which is building trust and credibility with each other that may take years. But, Trump went to the very last step of the diplomatic process without consulting his lower-level officials in the state department. But, if the President felt that he could handle the talks alone, then the very brunt of the talks depends on his personality--his rash and his oh so childish personality.
Trump dictates foreign policy based on his own personality. Trump initiated steel tariffs because he felt caged by his own administration, especially his economic advisors. As a result, countries lined up to request to be exempt from the steel tariff, an enraged China vowed a necessary response, steelworkers became even more destitute and most of all, the President's chief economic advisor, Gary Cohn, resigned. Trump did not consult any of his economic advisors for this decision. In fact, they advised against it. But Trump did it because he wanted to show that he could not be caged any longer.
When Trump accepted Kim's invitation, similar events of chaos followed. South Korea's Hoon, Chung, and Cho had to announce the news near the West Wing. Japan's Shinzo Abe planned a trip to the US immediately. White House officials scrambled for explanations when asked. And so did the experts.
Trump's impulsive personality created the talks, and his impulsive personality might very well end them. All the Korea experts in the state department left in the most crucial moment. Since they all left, the Trump administration had to decipher the diplomatic process all by themselves. As a result, they created misunderstandings, which, in turn, created events of chaos. But Trump's own impulsive personality dictated his decision to accept. For this reason, Trump's impulsive personality might very well dictate his decision to end the talks.
Don't be surprised if Trump takes everything back.