Mr. Trump made his post on Twitter, where he often tests out his first thoughts on developing issues in the United States and abroad, a day after North Korea’s young leader, Kim Jong-un, declared that the “final stage in preparations” was underway for a test of such a missile. Mr. Kim offered no time frame. North Korea has routinely tested short- and medium-range missiles, with some successes and many failures, but it has so far stopped short of testing a long-range missile, which could reach Guam or the West Coast of the United States.
“North Korea just stated that it is in the final stages of developing a nuclear weapon capable of reaching parts of the U.S.,” Mr. Trump wrote, somewhat misstating Mr. Kim’s warning. Pyongyang has already tested nuclear weapons underground; the latest threat concerned what Mr. Kim called a “test launch of an intercontinental ballistic missile.” But Mr. Kim also boasted last year that the North had conducted “the first H-bomb test,” and experts say there is no evidence for that claim.