Russian President Vladimir Putin shakes hands with North Korean Foreign Minister Choe Son Hui during a meeting in Moscow, Russia, Nov. 4. Reuters-Yonhap

South Korea's spy agency said, Wednesday, that it is closely monitoring the possibility of North Korean leader Kim Jong-un visiting Russia.

The National Intelligence Service (NIS) made the assessment after Russian President Vladimir Putin met with North Korean Foreign Minister Choe Son-hui at the Kremlin on Nov. 4, contrary to earlier reports that suggested no plans for such a meeting.

The agency shared the information with lawmakers during a closed-door meeting of the parliamentary intelligence committee, according to Rep. Lee Seong-kweun of the ruling People Power Party and Rep. Park Sun-won of the main opposition Democratic Party of Korea, who are leaders of the National Assembly's Intelligence Committee.

Choe's visit to Russia, where she met with her Russian counterpart Sergey Lavrov, and Putin, followed confirmation from South Korea and the U.S. that around 10,000 North Korean troops have been sent to Russia. Thousands of these troops have already been deployed to the front-line Kursk region.

"Putin greeted Choe on a national holiday. We believe the meeting touched upon important agendas, including sensitive ones like a potential visit by North Korean leader Kim Jong-un. It appears likely that both sides discussed more than exchanging cordial words," the NIS was quoted as saying by the lawmakers.

On Oct. 25, Kremlin spokesperson Dmitry Peskov said Kim visiting Moscow next year is a possibility, noting that high-level exchanges are always taking place with Pyongyang as its "close neighbor."

A TV screen shows file images of North Korean soldiers during a news program at Seoul Railway Station in Seoul, Oct. 18. AP-Yonhap

The NIS said some of the North Korean troops deployed to Russia in the Ukrainian war have been assigned to combat roles alongside Russia's Airborne Brigade and Marines.

"At least 11,000 North Korean soldiers completed acclimation training in Russia's northeastern regions and were relocated to Kursk in late October. With North Korean troops now being deployed to the front lines of the war in Ukraine, casualties are likely to emerge. We will closely monitor the extent of losses suffered by North Korean forces," it said.

The spy agency also confirmed additional exports of North Korean howitzers and multiple rocket launchers to Russia.

"We found out that North Korea has provided Russia with 170mm self-propelled howitzers and 240mm multiple rocket launchers in addition to artillery weapons. It is highly likely that North Korea also dispatched additional personnel to maintain and repair new weapons as they are not part of Russia's conventional arsenal.

North Korea and Russia have been strengthening military and other cooperation, with Kim and Putin holding summit talks in June in Pyongyang. They signed a new partnership treaty that includes a mutual defense clause.