Joseph Yun, U.S. special representative for North Korea policy who has advocated talks with the country, will retire as of Friday, State Department officials said Tuesday.Yun's departure comes as North Korea has expressed willingness to talk with U.S. President Donald Trump's administration for the first time.Yun has decided to retire for "personal reasons," said department spokeswoman Heather Nauert. But diplomatic sources said the move may reflect frustration over the Trump White House's perceived undercutting of the diplomatic efforts of the department.Secretary of State Rex Tillerson ha…READ FULL ARTICLE