(Ahn Young-joon | AP Photo) In this June 14, 2019 photo, hikers and journalists walk along the DMZ Peace Trail in the demilitarized zone in Goseong, South Korea. Eyeing a history-making photo opportunity, U.S. President Donald Trump on Saturday, June 29, 2019, issued a Twitter invitation to North Korea's Kim Jong Un to join him for a hand shake during a visit by Trump to the demilitarized zone with South Korea.