Ukraine’s HUR military intelligence agency on Saturday claimed North Korean mercenaries accidentally killed eight of their Russian partners in a “friendly fire” attack because of the “language barrier” between soldiers from the two countries.

According to HUR, a group of North Korean soldiers operating in Kursk targeted a Chechen Akhmat unit that was also fighting on Russia’s behalf. The “language barrier” presumably made it difficult for the Chechen unit to convince the North Koreans they were on the same side.

Kursk is the oblast (province) of Russia that was invaded by Ukrainian forces on August 6. The Ukrainian invasion caught Russia by surprise, forcing Moscow to draw up hasty plans for a counteroffensive.

In October, Russia reportedly made a deal with North Korea to bring thousands of North Korean troops to Russia for training and then deploy them against the Ukrainian troops occupying Kursk. The North Korean manpower would theoretically make it unnecessary for Russia to pull front-line combat units out of Ukraine to retake Kursk.

The Chechen Akhmat is a paramilitary unit from Chechnya that styles itself as an elite fighting force. The eccentric authoritarian ruler of Chechnya, Ramzan Kadyrov, lavished funds on training and equipping the Akhmat battalions so he could send them to Ukraine as a demonstration of his loyalty to Russian President Vladimir Putin.

The Russians were a bit wary of these Chechen forces at first but, as the Russian army became more desperate for manpower, it lowered its standards and accepted Kadyrov’s “elite troops.” The amount of action the Chechen troops have actually seen in Ukraine is a matter of debate.

An interesting wrinkle is that many of the latest Akhmat troops have not actually been Chechens, but rather veterans of the Wagner Group mercenary force, which was taken over by Putin’s regime after the death of Wagner founder Yevgeny Primakov in a highly suspicious plane crash in August 2023. Some Wagner personnel did not like the idea of working directly for Russia, or feared retribution from the Russians if their background as Wagner recruits became known, so they joined the Chechen Akhmat battalions instead.

The Ukrainian Defense Ministry said on Monday that at least 30 North Korean soldiers were killed fighting in Kursk over the weekend — a higher-than-expected casualty rate that purportedly left Russian commanders scrambling to send in reinforcements.

Ukrainian intelligence said the North Korean troops were particularly vulnerable to drone attacks, which Russian forces have learned to deal with during two bloody years of combat.

Ukrainian President Volodymyr Zelensky said on Saturday that the Russians have begun using a “significant number” of North Koreans in their assaults on Ukrainian positions in Kursk, and those North Korean units have suffered “noticeable losses.”

“We will defend ourselves, including against these North Koreans. And we will continue to act in coordination with all our partners to stop this war — to stop it decisively, with guaranteed peace,” Zelensky said.

Kremlin spokesman Dmitry Peskov refused to comment on reports of North Korean casualties on Monday. He referred questions about Ukraine’s claims to the Russian Defense Ministry, which also refused to comment.