Russian President Vladimir Putin and North Korea's leader Kim Jong Un pose for photographers during their meeting in Vladivostok, Russia, April 25, 2019. North Korean leader Kim Jong Un met Russian President Vladimir Putin on Thursday at a summit designed to show that Washington is not the only power able to set the agenda on Pyongyang's nuclear programme. Alexander Zemlianichenko/Pool via REUTERS

North Korean leader Kim Jong Un arrives to meet Russia's President Vladimir Putin at the Far Eastern Federal University campus at Russky Island in the far eastern city of Vladivostok, Russia April 25, 2019. The two men embarked on a day of talks on an island off the Russian Pacific city of Vladivostok two months after Kim's summit with U.S. President Donald Trump ended in disagreement, cooling hopes of a breakthrough in the decades-old nuclear row. REUTERS/Shamil Zhumatov

Russia's President Vladimir Putin shakes hands with North Korea leader Kim Jong Un at the Far Eastern Federal University campus at Russky Island in the far eastern city of Vladivostok, Russia April 25, 2019. Putin and Kim, in their first ever face-to-face encounter, shook hands outside the summit venue, a university campus, then sat down in a conference room to exchange greetings in front of the television cameras. REUTERS/Shamil Zhumatov

Russia's President Vladimir Putin walks with North Korea leader Kim Jong Un at the Far Eastern Federal University campus at Russky Island in the far eastern city of Vladivostok, Russia April 25, 2019. Putin said he hoped Kim's visit would "help us better understand by what means we can reach a settlement on the Korean peninsula, what we can do together, what Russia can do to support the positive processes now underway." REUTERS/Shamil Zhumatov

Russia's President Vladimir Putin walks with North Korean leader Kim Jong Un at the Far Eastern Federal University campus at Russky Island in the far eastern city of Vladivostok, Russia April 25, 2019. Kim, who had arrived in Vladivostok a day earlier on board his armoured train, told Putin the meeting would help strengthen and develop ties between Russia and North Korea, which share a long history of friendship. REUTERS/Shamil Zhumatov

Russian President Vladimir Putin and North Korea's leader Kim Jong Un shake hands during their meeting in Vladivostok, Russia, April 25, 2019. The summit in Vladivostok provides Pyongyang with an opportunity to seek support from a new quarter, Russia, and possible relief from the sanctions hurting its economy. For the Kremlin, the summit is a chance to show it is a global diplomatic player, despite efforts by the United States and other Western states to isolate it. Alexander Zemlianichenko/Pool via REUTERS