North Korean leader Kim Jong Un has arrived via rail in Russia where he is due to meet President Vladimir Putin.
Mr Kim left Pyongyang for Russia on Sunday on his private train, North Korea`s state media reported.
It is not known where the leaders will meet, as Mr Kim`s train is reportedly heading north, away from the city of Vladivostok.
A US official said they were expected to discuss an arms deal as Russia faces a Ukrainian counter-offensive.
The Kremlin said that the "fully fledged visit" would cover "bilateral relations, the situation in the region and in the global arena".
The meeting could take place as early as Tuesday local time - although the statement from the Kremlin said it would happen in the "coming days".
Mr Kim left his train to meet Russian representatives when it pulled into the border station of Khasan on Tuesday morning.
Footage shows him stepping off the train onto a red carpet to be greeted by a Russian delegation as a brass band plays.
He also met Alexander Kozlov, Russia`s minister for natural resources. According to Oleg Kozhemyako, a regional governor who released footage of the meeting, they discussed the potential launch this year of joint tourism and agricultural projects.
Mr Kim`s train is rumoured to include at least 20 heavy bulletproof carriages. The extra weight means the train is very slow - it can only travel at around 37mph (59 km/h).
The North Korean leader`s last trip abroad was to Vladivostok in 2019 for a summit with Mr Putin after the collapse of nuclear disarmament talks with the then-US president, Donald Trump.
The Vostochny cosmodrome, located in Russia`s far east near the border with China, has been suggested as the possible meeting place for the two leaders.
It is the country`s first commercial space centre and is one of Mr Putin`s pet projects.
The Russian president has announced he plans to go to the cosmodrome but has not confirmed that Mr Kim will meet him there. Responding to a question at the Eastern Economic Forum, Mr Putin said: "When I get there, you will know".
North Korea may seek co-operation from Russia on its space programme, which late last month failed a for second time to place a spy satellite in orbit after a rocket failure.
The White House said it had new information that negotiations between the Russia and North Korea were on a weapons deal "actively advancing".
National Security Council spokesman John Kirby said Russia`s Defence Minister Sergei Shoigu had tried to "convince Pyongyang to sell artillery ammunition" to Russia during a recent visit to North Korea.
Both sides have denied the reports.
The US and its allies have expressed concern over the possibility of closer military ties between Russia and Moscow.
Kremlin spokesman Dmitry Peskov said Russia would always act in its national interest.
"The interests of our two countries are important to us, and not warnings from Washington," he was quoted as saying by Russian media.
North Korea also wants food aid and possibly technology to help its banned nuclear and missiles programme, analysts say.
