SEOUL – North Korea confirmed Monday for the first time that it sent troops to Russia to support its war against Ukraine.

U.S., South Korean and Ukraine intelligence officials have said North Korea dispatched about 10,000-12,000 troops to Russia last fall. But North Korea hadn’t confirmed or denied its reported troop deployments to Russia until Monday.

Leader Kim Jong Un decided to send combat troops to Russia under a mutual defense treaty, the Central Military Commission of the ruling Workers’ Party said in a statement.

It cited Kim as saying the deployment was meant to “annihilate and wipe out the Ukrainian neo-Nazi occupiers and liberate the Kursk area in cooperation with the Russian armed forces.”

“They who fought for justice are all heroes and representatives of the honor of the motherland,” Kim said, according to the statement sent to state media.

In March, South Korea’s military said North Korea sent about 3,000 additional troops to Russia earlier this year, after its soldiers deployed on the Russian-Ukraine fronts suffered heavy casualties. South Korea’s Joint Chiefs assessed that around 4,000 North Korean soldiers had been killed or wounded.

Ukrainian President Volodymyr Zelenskyy earlier put the number of killed or wounded North Koreans at 4,000, though U.S. estimates were lower at around 1,200.

In March, Kim expressed his unwavering support for Russia’s war in Ukraine during a meeting with a top Russian security official, Sergei Shoigu, in Pyongyang. State media reports said Kim and Shoigu reaffirmed their commitment to uphold the mutual defense treaty agreed upon last year. Russian Deputy Foreign Minister Andrei Rudenko told Russian media the governments were discussing a potential visit by Kim to Moscow.

North Korea has been supplying a vast amount of conventional weapons to Russia as well. South Korea, the U.S. and their partners worry that Russia could reward North Korea by transferring high-tech weapons technologies that can sharply enhance its nuclear weapons program. North Korea is expected to receive economic and other assistance from Russia as well.

North Korean soldiers are highly disciplined and well trained, but observers say they’ve become easy targets for drone and artillery attacks on Russian-Ukraine battlefields due to their lack of combat experience and unfamiliarity with the terrain.

Still, Ukrainian military and intelligence officials have assessed that the North Koreans are gaining crucial battlefield experience and have been key to Russia’s strategy of overwhelming Ukraine by throwing large numbers of soldiers into the battle for Kursk.