Russia's president and Kim Jong Un held talks on Wednesday during which they are believed to have explored a range of "sensitive topics".
Vladimir Putin held talks with his North Korean counterpart on Wednesday, during which Kim Jong Un vowed his “full and unconditional support” for Russia's war in Ukraine.
"Russia has risen to a sacred fight to protect its sovereignty and security against the hegemonic forces," he said. "North Korea supports all Putin's decisions."
"I'm sure we will remain together in [the] fight against imperialism," Kim said earlier, expressing his gratitude to the Russian leader for the visit.
The two men reportedly discussed a range of "sensitive topics", according to Kremlin spokesman Dmitry Peskov.
When asked about the possibility of military cooperation, Putin suggested everything was on the table, Russia's state-owned news agencies reported.
The Russian president, in an interview with state television after the meeting, said there was a possibility of military-technical cooperation between the two countries.
The pair visited a rocket assembly and launch site, known as the Vostochny Cosmodrome, with the Russian leader promising to help North Korea build satellites.
"That's why they came here. The leader of North Korea shows great interest in rocket technology, they are also trying to develop their own space programme," Putin told reporters.
Kim and his Russian counterpart also reportedly discussed "trade relations" and "international affairs" at the space facility, which is tucked in a forest near the Chinese border.
Both international pariahs, Moscow and Pyongyang increasingly need one another.
With Russia heavily sanctioned, Putin wants North Korean ammunition for his grinding invasion of Ukraine, while Kim desperately needs food and humanitarian aid, as COVID has left his country grappling with chronic food shortages.
The United States and South Korea both expressed concerns that Pyongyang will supply Russia with weapons and ammunition.
The US has previously accused North Korea of providing weapons to Russia, though it is not clear if any deliveries have been made.
Speaking to Euronews in September, Fyodor Tertitskiy, an expert in North Korean history and military, was skeptical a meaningful deal could be struck since much depends on whether China approves.
He also claimed Pyongyang has not seen any economic wins from supporting Moscow - with an "actual trade balance of zero" between the two in 2022 - despite North Korea publically backing the Ukraine invasion and annexation of Crimea.
The visit was Kim's first trip abroad since the start of the Covid-19 pandemic. He met Putin on his last foreign visit to Vladivostok in 2019.
“It is entirely credible that North Korea has large stocks of ammunition that would be compatible with the artillery systems being used by Russian forces. It also has the production lines and personnel to produce more at scale," said Siemon Wezeman of the Stockholm International Peace Research Insitute (SIPRI) in a statement sent to Euronews.
“However, if Russia were indeed to strike such a deal with North Korea, it would be an unequivocal violation of international law."
Under a 2009 United Nations Security Resolution, it is forbidden to acquire weapons from North Korea.
Kim arrived in a black limousine on Wednesday and the two men shook hands with smiling faces and exchanged a few words.
The Russian president reportedly congratulated Kim on multiple North Korean anniversaries, including 75 years since the country was founded in 1948.
“Whether any deal is struck remains to be seen. Both sides would have strong reasons for secrecy. We will not know for sure until there is hard evidence that Russia has used North Korean arms and ammunition on the battlefield in Ukraine," said Wezeman from SIPRI.
"However, it is worth noting that despite similar allegations a year ago and rumours at the end of last year that the Wagner Group had acquired North Korean arms, SIPRI researchers have not seen any public evidence to back it up, such as evidence of it being used on the battlefield in Ukraine - something that surely both Kyiv and Washington would be eager to publicise.”
Earlier, South Korea and Japan announced they had detected two short-range ballistic missiles launched from North Korea's east coast.
US analyst Ankit Panda reacted to the test on X, describing the "launch without Kim Jong Un in the country" as "fascinating".
"This is a first," he said.
North Korea has carried out a series of banned weapons tests since the start of the year, most recently involving two short-range ballistic missiles on 30 August.
Pyongyang last month failed in its second attempt to put a spy satellite into orbit.
In response, South Korea and the United States have increased defence cooperation, holding joint exercises and naval manoeuvres with Japan.