European Commission President Ursula von der Leyen on Monday warned that the deployment of North Korean troops to support Russia in its war in Ukraine threatened global peace.

"The security of Europe and East Asia are interlinked. North Korean soldiers are deployed to support Russia's war of aggression. It's a grave escalation in this war and a threat to global peace. We will respond together with our like-minded partners," von der Leyen said on X after a phone call with South Korean President Yoon Suk Yeol.

NATO Secretary-General Mark Rutte has confirmed that North Korean troops have been deployed to Russia days after Ukrainian military intelligence recorded the presence of North Korean units in the Kursk border region.

The Ukrainian military has been operating in the Kursk region since staging a major incursion in August.

Rutte said on Monday that the move represented “a significant escalation” of Pyongyang’s involvement in “Russia’s illegal war” in Ukraine, a breach of United Nations Security Council resolutions and a “dangerous expansion” of the conflict.

“The deepening military cooperation between Russia and North Korea is a threat to both Indo-Pacific and Euro-Atlantic security,” Rutte told reporters after NATO officials and diplomats were briefed by a South Korean delegation.

South Korean President Yoon Suk-yeol sounded the alarm about the troops during telephone calls with Rutte and European Commission President Ursula von der Leyen and added that Seoul would continue to consult closely with NATO.

US President Joe Biden also called the deployment of North Korean troops to Russia “dangerous”.

“A portion of those soldiers have already moved closer to Ukraine, and we are increasingly concerned that Russia intends to use these soldiers in combat or to support combat operations against Ukrainian forces in Russia’s Kursk Oblast,” Pentagon Deputy Press Secretary Sabrina Singh told journalists.