US negotiators dangled a Trumpian carrot before North Korean diplomats during nuclear talks two weeks ago: a promise to complete and expand a tourist resort that has been a favorite project of Kim Jong-un. The American diplomats offered the development help in exchange for denuclearization, according to the South Korean newspaper Hankook Ibo. The under-construction Kalma tourist area on North Korea’s east coast includes dozens of hotels, a shopping mall, and an indoor water park under a glass pyramid roof. Trump, who touted the Hermit Kingdom’s “great beaches” after his 2018 summit with Kim in Singapore, said the area “could...