South Korea has intelligence that North Korea has suffered losses among its troops dispatched to aid in Russia’s war on Ukraine.

The National Intelligence Service on Monday confirmed for the first time North Korean troops fighting Ukraine have been killed and wounded, without providing how many.

In a Nov. 20 briefing to the National Assembly, the NIS said North Korean troops were deployed in the Russian province of Kursk near the border with Ukraine, with some participating in battles.

According to a report by RBC-Ukraine on Saturday, North Korean soldiers appeared to have died after a Ukraine attack using UK-supplied Storm Shadow missiles.

The Ukrainian news agency, which was quoting US-based Global Defense Corp, said a Storm Shadow missile strike on the Kursk region killed about 500 North Korean soldiers. The missile landed on a warehouse housing North Korean troops, it said.

The NIS said last month that Pyongyang was due to send about 10,900 of its troops, most of them from special forces, to fight alongside Russia. Many of the North Korean soldiers sent to the war were in their late teens or early 20s, according to the NIS.

The NIS added that large casualties were feared as the North Korean military was not trained to fight in a modern war.

The NIS revealed at the time that it had intelligence that North Korean generals such as Kim Yong-bok, deputy chief of the general staff for special forces operations, might be aiding Russia on the front lines of the war.

The Institute for National Security Strategy, a think tank affiliated with the NIS, stated in a report Friday that Pyongyang may dispatch additional troops to help with Moscow’s cyber operations against Kyiv.

According to the INSS report, North Korea and Russia were becoming more aggressive in their “cognitive warfare,” which is when false information is used to mislead the enemy.

“The military pact signed during Russian President Vladimir Putin’s visit to Pyongyang in June specifies cooperation in cyber defense, and North Korea may provide additional troops for cyber operations,” the report said.