SEOUL (Kyodo) -- South Korea summoned Russia's ambassador to Seoul on Monday to lodge a protest over North Korea's recent dispatch of troops to help Moscow in its ongoing war with Ukraine, the South Korean Foreign Ministry said.

South Korean First Vice Foreign Minister Kim Hong Kyun pointed out that the current military ties between North Korea and Russia pose a great threat not only to South Korea but also to the international community, the ministry said in a press release.

Growing military cooperation between Pyongyang and Moscow in recent years has not only led to the transfer of military supplies but the actual deployment of North Korean troops.

Kim "strongly urged the immediate withdrawal of North Korean forces and the cessation of related cooperation," the ministry said.

Russian Ambassador Georgiy Zinoviev was quoted by the ministry as saying he will convey South Korean government's position to Moscow.

Last Friday, South Korea's local media reported about 12,000 soldiers had been deployed from Pyongyang to Vladivostok in Russia's Far East, citing the National Intelligence Service, which confirmed North Korea's involvement in the war. The spy agency also said that the dispatch of a second unit is expected to take place soon.