Kim Jong Un’s heavily-armored private train has crossed into Russia ahead of an expected and closely-watched summit with Russian President Vladimir Putin, state media reported Tuesday, amid warnings from the United States that the two leaders could strike an arms deal.

The train was traveling north through Primorsky Krai in the Far East region of the country, Russian state news agency RIA reported. South Korea’s Defense Ministry said it believed the North Korean leader entered Russia early Tuesday morning local time.

A video shared by Russia Today on Monday and geolocated by CNN showed the train purportedly carrying Kim near the Russian-North Korean border by the Tumen river.

A one to one between Kim and Putin, expected to take place in Russia’s far east, would be a significant development, analysts say, bringing together two leaders who are increasingly isolated on the world stage.

Russia desperately requires fresh supplies of ammunition and shells after more than 18 months of war in Ukraine has left its military battered, while North Korea, which has faced years of international sanctions over its nuclear weapons program, is short of everything from hard cash and food to missile technology.

The meeting could lead to Pyongyang getting its hands on the sort of weapons two decades’ worth of United Nations’ sanctions have barred it from accessing, especially for its nuclear-capable ballistic missile program.

Kremlin spokesperson Dmitry Peskov said that bilateral relations between the nations will be a priority of the meeting, which will be a “full-blown visit, with talks between the two delegations”.

The talks will also touch upon “sensitive areas”, Peskov added, while a formal dinner is also planned in honor of Kim’s arrival.