Ukrainian, South Korean and US sources all report that North Korea has transferred at least 10,000 soldiers to Russia, with some reports mentioning numbers up to 12,000.

Russian President Vladimir Putin has said he reserves the right to deploy North Korean soldiers: "It is our sovereign decision."

Ukraine and its supporters strongly condemned the deployment of North Korean troops, fearing a further escalation of the war.

What do we know about where the soldiers are?

The troops were initially deployed to Russia's far east for training. According to media reports, they will learn the most important military orders in Russian, among other things. They are also to wear Russian uniforms.

Some of the soldiers are reported to have arrived in Russia's Kursk region, close to the border with Ukraine. Ukraine's army advanced into Kursk with a surprise attack at the beginning of August and took control of numerous villages. The Russian army wants to recapture the area, and could rely on the support of North Korean soldiers.

Why does Putin need North Korean troops?

Russian casualties in Ukraine are high. According to British military intelligence, an average of 1,271 Russian soldiers were killed or seriously wounded every day in September 2024. In total, more than 600,000 are estimated to have been killed since the start of the war in February 2022.

NATO Secretary General Mark Rutte has said Russia is "not in a position" to maintain its assault on Ukraine "without foreign support."

Putin urgently needs more soldiers. However, observers are also wondering whether 10,000 North Koreans can make up for the heavy Russian losses over the long term.

How could North Korean soldiers be deployed?

South Korean intelligence agencies presume that the North Korean troops in question are highly trained special forces. How and where exactly they will operate is still unclear.

"The North Korean military is designed to fight on the Korean Peninsula and not to be deployed abroad," Mark Cancian, a senior adviser to the international security program at the US think tank Center for Strategic and International Studies (CSIS), told DW.

Cancian believes that none of the soldiers have ever been abroad before.

He said the soldiers could be given special tasks such as in the field of logistics or in connection with North Korean missiles delivered to Russia.

Ukrainian President Volodymyr Zelenskyy said he believed that the North Korean troops will be sent to the front. "Ukraine will effectively be forced to fight against North Korea in Europe," he said.

Do North Korean troops in Ukraine violate international law?

By waging war against Ukraine, Russia is violating international law. And if North Korea were to support the Russian war of aggression with its own soldiers, "then North Korea would also be acting in violation of international law," Claus Kress, professor of criminal law and international law at the University of Cologne in Germany, told DW.

Whether the North Korean soldiers are deployed in Russia's Kursk region, in regions annexed by Russia or in other Ukrainian regions makes no difference, Kress said. In all of these places, North Korea would at least be aiding and abetting a use of force in violation of international law.

Does deployment in Ukraine make North Korea a party to the conflict?

This depends on the command authority over the North Korean soldiers, Kress said.

"If Russia had sole command, the actions of these soldiers would be solely attributable to Russia under international law," he said.

And North Korea would therefore not be a party to the conflict, even if the soldiers deployed by North Korea were to take part directly in the hostilities between Russia and Ukraine, he added.

"It would be different if North Korea retained command of its deployed soldiers, either alone or together with Russia," Kress said. North Korea would then become a party to the conflict through the direct involvement of its soldiers in the hostilities.

In this case, Kress said, Ukraine could also defend itself on North Korean territory "to a necessary and proportionate extent."  This means, in other words, to take military action against North Korea. If the use of force reaches a certain intensity, this would constitute an armed attack by North Korea against Ukraine.

What is North Korea getting in return?

With 1.3 million soldiers, North Korea has one of the largest armies in the world. The deployment of the troops could provide the North Korean army with combat experience, which would further increase its threat potential vis-a-vis South Korea.

Prior to the deployment of troops, North Korea had already supplied Russia with several million rounds of ammunition and numerous ballistic missiles, as Russian ammunition depots had been depleted during fighting in Ukraine.

The Russian quid pro quo is said to include food, fuel and possibly satellite technology.

Following the deployment of troops, North Korean dictator Kim Jong Un could try to ramp up his demands once again, said Victor Cha, the Korea chair at the CSIS.

Kim is very interested in cutting-edge military technology — especially intercontinental missiles and nuclear submarines. "Kim is not stupid. He knows that Putin needs both the ammunition and the troops from North Korea. So why not ask for a higher price?" Cha said.

 Whether Putin then complies with this request is another matter.

What connects Russia and North Korea?

Moscow and Pyongyang maintained close relations during the Cold War. Putin and Kim picked up on this again after Moscow launched the war in Ukraine.

North Korea's support for Russia became clear early on when the country was one of only five to vote against the resolution condemning Russia's attack on Ukraine at the UN General Assembly in March 2022.

By closing ranks with Russia, the internationally isolated North Korea was able to obtain urgently needed goods and technology, while Putin received ammunition and weapons for his army.

The cooperation culminated in a mutual defense pact in June 2024.

How has NATO responded?

On October 28, Secretary General Rutte demanded that Russia and North Korea "stop these actions immediately."

He said the deployment of North Korean troops was "a further violation of UN Security Council resolutions and a dangerous expansion of the Russian war."

Rutte also sees the deployment of North Korean troops in Kursk "as a sign of Putin's growing desperation." He has pledged ongoing NATO support to Ukraine.

NATO must respond to this "unimaginable provocation," Marie-Agnes Strack-Zimmermann, a German member of the European Parliament, told Germany's Rheinischen Post newspaper.

"The axis of evil is active. Who can guarantee that North Korean soldiers won't be deployed in the Baltic States in a few years' time or that the Chinese won't buy them in to attack Taiwan?" she said.

What does this all mean for the EU?

The sending of troops to Russia will have long-term consequences for North Korea's relations with the European Union, Cha said. "Europe has traditionally been North Korea's gateway to the West," he said, "and was seen by Pyongyang as more 'neutral' than the United States."

North Korean diplomats are present in most European countries, Cha said. "North Korea's decision to send troops to kill Europeans will not soon be forgotten in European capitals."

This article was originally written in German.