A train, thought to be carrying the North Korean dictator, has departed for Russia, reported South Korean media, with a Kim-Putin meeting possible as early as Tuesday.
The trip, if confirmed, would be Kim’s first visit abroad in more than four years and the first since the Covid pandemic.
Last week, US officials said the two countries were arranging a meeting between their leaders within a month, as they looked to deepen ties amid their deepening confrontation with the West.
Russian news agency Interfax had earlier reported Kim was expected to visit the Far East “in the coming days".
Putin could use the meeting to seek more supplies of North Korean artillery and other ammunition as Russia wages its brutal war in Ukraine.
Kim Jong Un could in turn seek badly-needed energy and food aid and advanced weapons technology.
There are concerns among Western officials that any potential Russian technology transfers could increase the threat posed by North Korea.
Last week, the regime claimed to have launched a new nuclear-capable attack submarine, in a move it said was designed to “strike fear” into the hearts of South Korea and the US.
Mr Kim’s last trip abroad in 2019 was also to Vladivostok for his first summit with Putin after the collapse of North Korea’s nuclear disarmament talks with former US President Donald Trump.
In July, Russia’s defence minister Sergei Shoigu visited North Korea’s capital Pyongyang and toured a weapons exhibition that featured combat and surveillance drones.
North Korea has backed Russia over the war in Ukraine, blaming the US for ‘forcing’ Moscow to invade Ukraine to protect its security interests.
It is also among the few countries which has recognised the Russian occupation of Donetsk and Luhansk.