North Korean leader Kim Jong Un and Chinese President Xi Jinping raise a toast in Beijing, China, in this undated photo released June 20, 2018 by North Korea's Korean Central News Agency.

North Korean leader Kim Jong Un walks with Chinese President Xi Jinping in Beijing, China, in this undated photo released June 20, 2018 by North Korea's Korean Central News Agency.

Chinese President Xi Jinping speaks during a meeting with North Korean leader Kim Jong Un (not pictured) in Beijing, China, in this undated photo released June 20, 2018 by North Korea's Korean Central News Agency.

North Korean leader Kim Jong Un and his wife Ri Sol Ju stand beside Chinese President Xi Jinping and his wife Peng Liyuan in Beijing, China, in this undated photo released June 20, 2018 by North Korea's Korean Central News Agency.

North Korean leader Kim Jong Un and Chinese President Xi Jinping attend a meeting in Beijing, China, in this undated photo released June 20, 2018 by North Korea's Korean Central News Agency.

North Korean leader Kim Jong Un and his wife Ri Sol Ju walk upon arriving in Beijing, China, in this undated photo released June 20, 2018 by North Korea's Korean Central News Agency. KCNA via REUTERS

North Korea's leader Kim Jong Un gets into a car as he leaves North Korean embassy in Beijing, China, in this photo taken by Kyodo June 20, 2018.

Police motorcycles accompany a motorcade believed to be carrying North Korean leader Kim Jong Un in Beijing, China June 19, 2018.

North Korean leader Kim Jong Un walks beside Chinese President Xi Jinping in Beijing, China, in this undated photo released June 20, 2018 by North Korea's Korean Central News Agency.

Police motorcycles accompany a motorcade believed to be carrying North Korean leader Kim Jong Un through Chang'an Avenue in central Beijing, China June 20, 2018. Picture taken through a window.

A vehicle of a motorcade believed to be carrying North Korean leader Kim Jong Un makes its way through Chang'an Avenue in central Beijing, China June 20, 2018. Picture taken through a window.

Police motorcycles accompany a motorcade believed to be carrying North Korean leader Kim Jong Un through Fuxingmennei Street in central Beijing, China June 19, 2018. Picture taken through a window.

A car believed to be carrying North Korean leader Kim Jong Un drives down Chang'an Avenue towards Tiananmen Square in Beijing, China June 19, 2018.

North Korean leader Kim Jong Un speaks during a meeting with Chinese President Xi Jinping (not pictured) in Beijing, China, in this undated photo released June 20, 2018 by North Korea's Korean Central News Agency.

North Korean leader Kim Jong Un and his wife Ri Sol Ju pose beside Chinese President Xi Jinping and his wife Peng Liyuan in Beijing, China, in this undated photo released June 20, 2018 by North Korea's Korean Central News Agency.

North Korean leader Kim Jong Un and his wife Ri Sol Ju are welcomed upon their arrival in Beijing, China, in this undated photo released June 20, 2018 by North Korea's Korean Central News Agency.

A vehicle of a motorcade believed to be carrying North Korean leader Kim Jong Un makes its way through Fuxingmennei Street in Beijing, China June 19, 2018. Picture taken through a window.