NATO Secretary-General Mark Rutte said Monday that the deployment of North Korean troops to Russia to bolster Moscow’s war effort in Ukraine was a sign of Russian President Vladimir Putin’s “growing desperation.”

“Today, I can confirm that North Korean troops have been sent to Russia, and that North Korean military units have been deployed to the Kursk region,” Rutte told reporters at a press conference in Brussels.

The move marks “a significant escalation” in North Korea’s involvement in the conflict and represents “a dangerous expansion of Russia’s war,” Rutte said.

Rutte said NATO was “actively consulting within the alliance, with Ukraine, and with our Indo-Pacific partners,” on the developments. He said he was due to talk soon with South Korea’s president and Ukraine’s defense minister.

“The deepening military cooperation between Russia and North Korea is a threat to both the Indo-Pacific and Euro-Atlantic security,” Rutte said.

Adding thousands of North Korean soldiers to Europe’s biggest conflict since World War II will pile more pressure on Ukraine’s weary and overstretched army, as well as stoking geopolitical tensions in the Korean Peninsula and the wider Indo-Pacific region, including Japan and Australia, Western officials say.

Russian President Vladimir Putin is keen to reshape global power dynamics. He sought to build a counterbalance to Western influence with a summit of BRICS countries, including the leaders of China and India, in Russia last week.

Ukrainian President Volodymyr Zelenskyy, citing intelligence reports, claimed last Friday that North Korean troops would be on the battlefield within days. He previously said his government has information that some 10,000 troops from North Korea were being readied to join Russian forces fighting against his country.

Days before Zelenskyy spoke, American and South Korean officials said there was evidence North Korea had dispatched troops to Russia. The U.S. said around 3,000 North Korean troops had been deployed to Russia for training.

contributed to this report.