North Korea sent containers to Russia that could contain as many as 4.8 million artillery shells, South Korean Defense Minister Shin Won-sik said in an interview with Bloomberg published on June 14.
With Russia's military stocks running low due to extensive use in Ukraine, North Korea has been shaping up as Russia's leading weapons supplier.
Seoul spotted at least 10,000 containers being shipped from North Korea to Russia, Won-sik said. Pyongyang also sent dozens of ballistic missiles that Moscow troops launch against Ukraine, he added.
Both Kyiv and Washington have previously said that Russia has been using North Korean-produced missiles to attack Ukraine. In March, Ukrainian prosecutors reported that Russia had fired around 50 such missiles to attack six Ukrainian oblasts since the beginning of the full-scale invasion.
In exchange for the ammunition, Russia reportedly provided North Korea with technology to help it deploy spy satellites as well as tanks and aircraft.
Russian President Vladimir Putin will reportedly visit Vietnam and North Korea soon. He will probably want to receive more shells during the trip and seek to strengthen security cooperation with Pyongyang, the South Korean minister said.
South Korea's intelligence service is conducting a review into suspicions that North Korea has provided Russia with artillery shells and other weaponry manufactured in the 1970s, the country's National Intelligence Service (NIS) said on May 12.