Kim Jong Un, Donald Trump

FILE - This combination of photos shows North Korean leader Kim Jong Un on April 15, 2017, in Pyongyang, North Korea, left, and U.S. President Donald Trump in Washington on April 29, 2017. The notion of a substantive sit-down between North Korean leader Kim Jong Un and U.S. President Donald Trump – the most gazed-upon figures of this moment in the planet's history – is a staggering prospect and a potential logistical nightmare if the two countries ever tried to make it happen. (AP Photo/Wong Maye-E, Pablo Martinez Monsivais, Files)