SEOUL (NYTIMES) - A senior American negotiator arrived in North Korea on Wednesday (Feb 6) to sort out crucial details for a nuclear summit meeting in Vietnam between United States President Donald Trump and the North's leader, Kim Jong Un, with only three weeks to go before the talks take place. Mr Stephen Biegun, the Trump administration's special representative for North Korea, arrived in Pyongyang, the North's capital, around the time that Mr Trump announced in his State of the Union address that he and Mr Kim would meet for a second time on Feb 27-28 in Vietnam. Mr Beigun's...