A photo released by the official North Korean Central News Agency (KCNA) shows Kim Jong-un (L), chairman of the Workers' Party of Korea in Pyongyang, North Korea, 16 April 2019. EPA
A photo released by the official North Korean Central News Agency (KCNA) shows Kim Jong-un (L), chairman of the Workers' Party of Korea in Pyongyang, North Korea, 16 April 2019. EPA

Activity detected at North Korea's main nuclear site, says US monitor