WASHINGTON—Secretary of State Mike Pompeo headed to North Korea on Thursday for a fourth visit in which he is expected to press the government to deliver on its promises to denuclearize the Korean Peninsula.
Mr. Pompeo’s visit follows reports over the past week that North Korea is rapidly expanding a major missile-manufacturing plant and upgrading a nuclear research facility. There are also signs that trade between North Korea and China is on the rise, easing economic pressure on Pyongyang.
...