Kim arrives in Russia for talks

On Tuesday, a US State Department spokesperson said the United States is aware of the reports that Kim has left for Russia, without giving further comments, The Associated Press reported.

Cui Heng, a Russian studies researcher at East China Normal University, said the main agenda for Kim is to ask for Moscow's support in pressuring Washington over sanctions relief, which Cui said is the sticking point in denuclearization talks.

After the Hanoi summit, Trump said US sanctions will be lifted after Pyongyang gives up nuclear weapons.

Cui said Moscow and Pyongyang both favor a phased, incremental approach to the nuclear disarmament, while Washington calls for Pyongyang to take sweeping denuclearization steps before any rewards are given.

As Pyongyang's traditional ally, Moscow will seek to "consolidate positive trend" amid the stalled progress, as it advocates peaceful settlement and opposes Western countries' "arm-twisting approaches", Cui added.

Meanwhile, a Russian expert said the meeting could also focus on bilateral economic cooperation. Georgy Toloraya, director of the Asian Strategy Center at the Russian Academy of Sciences, said although the meeting is expected to be brief, the symbolic significance is vital.

"This is the first contact at the highest level with the head of a neighboring country, which plays a leading role in the process of settling the crisis near Russia's borders," he said.