When the North Korean leader Kim Jong-un visited President Vladimir V. Putin of Russia four years ago in their only previous meeting, it was mostly for diplomatic show.
But this week he will meet Mr. Putin with the ability to supply something the Kremlin desperately needs: munitions that could help Russian forces fighting in Ukraine.
In return, Russia could give North Korea some of what it needs — food, oil or hard currency — and turn a relationship long limited to modest trade and public displays of cooperation into something more substantive.
That kind of transaction, with mutual benefits for both parties, would signal “the real end of an era with the relationship that started in 1990,” said Fyodor Tertitskiy, leading researcher at Kookmin University in Seoul.
Since then, Mr. Tertitskiy said, the ties between the two countries had featured a lot of “talk and no real trade,” noting that a deal where Russia provides North Korea with something of value in exchange for munitions would mark a departure.
It was not clear when the meeting would occur, but a train similar to the one Mr. Kim has preferred to use for his rare trips out of the country was photographed near the border between the two countries on Monday, heading in the direction of Vladivostok, the east Russian port city where Mr. Putin has been attending an economic conference. It was also the site of their 2019 meeting.
Another meeting with Mr. Kim will be the latest example of Mr. Putin’s efforts to strengthen ties with leaders similarly opposed to the Western world, some of whom can help Russia in its war against Ukraine.
Mr. Putin made a rare international trip to Iran last year to meet with Ayatollah Ali Khamenei, Iran’s supreme leader, as well as the country’s president, as Russia became increasingly isolated from the West because of the invasion.
In the months since, Iran has become a critical supplier of drones to Moscow, which Russian forces have used against Ukraine, both on the battlefield and in attacks on civilian infrastructure.
Mr. Putin has also appeared with the Kremlin’s closest ally, President Aleksandr G. Lukashenko of Belarus, who gave Russia access to his country’s territory to launch its invasion of Ukraine in February of last year.
The Pentagon said this month that Russia had specifically asked North Korea for ammunition, noting that the request was the result of problems Moscow has been having with replenishing its battlefield supplies.
Russia’s defense minister, Sergei K. Shoigu, visited North Korea in July on a trip that U.S. officials at the time said was aimed at setting up an armaments deal.
North Korea has one of the world’s largest armies, despite having a population of only about 26 million people. The country operates on a wartime footing at all times, and artillery would be a critical piece of any renewed war with South Korea. Analysts believe that North Korea has a surplus of ammunition since it has not fought a war since 1953, when the Korean Armistice was signed.
Petr Akopov, a pro-war columnist for the Russian state news agency RIA Novosti, suggested in a recent article that Russia could “unofficially” transfer military technology to Pyongyang and welcome North Korean builders into occupied areas of Ukraine, in exchange for ammunition and certain types of missiles.
“All of this is hampered to one degree or another by U.N. Security Council sanctions, but there are always options for circumventing them,” Mr. Akopov wrote.
Mr. Akopov added, “The world is changing, and those countries that have challenged the Western world order will not be able to change it by playing by its rules.”