President Donald Trump with Kim Yong-chol, far left, the former North Korean intelligence chief and top nuclear arms negotiator, and Secretary of State Mike Pompeo, center, on the South Lawn of the White House in Washington, June 1, 2018. Planning the coming summit meeting between President Trump and Kim Jong-un to discuss North Korea’s nuclear future will require deciding countless, infinitesimal details, often via tricky diplomatic negotiations. (Tom Brenner/The New York Times)