South Korea has called on Russia’s ambassador to Seoul to protest “in the strongest terms” against the reported deployment of thousands of North Korean troops to help Russia in its war against Ukraine.

First Vice Foreign Minister Kim Hong-kyun told Russian envoy Georgy Zinoviev that the participation of North Korean troops in the war violated UN resolutions and demanded their immediate withdrawal, the South said Korean Foreign Ministry said in a statement Monday.

“We condemn North Korea’s illegal military cooperation, including the sending of troops to Russia, in the strongest terms,” Kim said, adding that the deployment posed a serious threat to the security of South Korea and other countries. “We will respond together with the international community by mobilizing all available resources against acts that threaten our fundamental security interests.”

The decision to involve Zinoviev reflects growing anger in South Korea, Ukraine and the US over the apparent deployment of North Korean troops as part of a secret military deal struck this year by Russian President Vladimir Putin and the North Korean leader Kim Jong. -on.

South Korea’s national intelligence agency said last week that North Korea had sent an initial contingent of 1,500 special forces troops to the Russian Far East for training at local military bases, adding that they were expected to would go on active duty in the war in Ukraine.

On Friday, the spy agency said North Korea planned to send about 12,000 special forces to support Russia, possibly to make up for significant losses of Russian troops and a lack of replacements.

It also released satellite images that it said show the first deployment of elite North Korean soldiers who were moved to Vladivostok by Russian military ships between October 8 and 13.

“North Korea transported its special forces to Russia via a Russian Navy transport ship, confirming the beginning of North Korea’s military participation,” the report said.

The White House could not confirm reports that North Korean troops were fighting for Russia, but a National Security Council spokesman said if true it would “mark a dangerous development in Russia’s war against Ukraine.”

Ukrainian officials released a video on Monday claiming dozens of North Korean recruits are lining up to pick up Russian military fatigues.

The video, published by the Center for Strategic Communications and Information Security – part of Ukraine’s Ministry of Culture and Information – appears to show soldiers waiting to collect bags, clothes and other items from Russian military personnel.

“We received this video from our own sources,” Ihor Solovey, the center’s head, told the Associated Press, adding that he could not provide additional verification due to security concerns.

“The video clearly shows North Korean citizens being given Russian uniforms under the direction of the Russian military,” he said. “For Ukraine, this video is important because it is the first video evidence showing North Korea participating in the war on Russia’s side. Now not only with weapons and grenades, but also with personnel.”

The center claimed the images were taken by a Russian soldier in recent days. It was not said how the clip was obtained and the location is unknown.

Putin and Kim have not disclosed details of their deal, which they agreed during the Russian president’s visit to Pyongyang in June. The countries have also denied that North Korea has supplied Russia with ammunition and missiles.

These denials have been challenged by Ukrainian, South Korean and U.S. officials. On Friday, South Korean intelligence said North Korea has supplied Russia with more than 13,000 containers of artillery shells, rockets, anti-tank missiles and other deadly weapons since August.

Ukrainian President Volodymyr Zelensky said North Korean involvement in the war would “significantly increase” the threat level and instability in the region.

During his late-night video address on Sunday, Zelenskyy said satellite and video evidence from North Korean forces proved that another country had actually entered the war and demanded a strong response from Kiev’s allies.

“I am grateful to the leaders and representatives of states who do not close their eyes and speak candidly about this cooperation for the sake of a greater war,” he said. “We expect a normal, fair and strong response from our partners.”

North Korea has not commented on reports that it is sending troops to fight alongside Russia.