American and South Korean officials have said that there is evidence North Korea has dispatched troops to Russia in a potential escalation of the nearly three-year-old war with Ukraine.

If the soldiers’ goal is fighting with Russia in Ukraine, it would be the first time a third country puts boots on the ground in the war.

Other countries on both sides of the divide have sent military aid, including weapons and training: Iran has supplied Russia with drones, and Western nations have provided Ukraine with modern weapons and financial and humanitarian assistance.

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Russian President Vladimir Putin and North Korea’s leader Kim Jong Un smile during their meeting at the Pyongyang Sunan International Airport (Gavriil Grigorov/AP)

South Korea’s spy chief told legislators that 3,000 North Korean troops were being trained to use equipment including drones before being sent to fight in Ukraine.

United States Defence Secretary Lloyd Austin told reporters during a visit to Rome that “we are seeing evidence that there are North Korean troops” who have gone to Russia.

“What exactly they’re doing — left to be seen,” Mr Austin said.

Neither Austin nor South Korean National Intelligence Service Director Cho Tae-yong provided details about how they knew about the North Korean troops, and many questions surround the impact of North Korean participation.

– What do we know about the North Korean troops?

North Korean troops were arriving in Russia’s Kursk region as early as Wednesday to help Russian troops fight off a Ukrainian border incursion, Ukraine Military Intelligence Directorate head Kyrylo Budanov told the online military news outlet The War Zone on Tuesday.

Ukrainian President Volodymyr Zelensky told reporters on Monday that North Korean officers and technical personnel have already been spotted in Russian-occupied territories. He did not specify when.

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Soldiers march in a parade for the 70th anniversary of North Korea’s founding day in Pyongyang (Ng Han Guan/AP)

“I believe they sent officers first to assess the situation before deploying troops,” Mr Zelenskyy said.

He has cautioned that the participation of a third country could escalate the conflict into a world war.

Mr Austin said that it would be a “very, very serious issue” if Pyongyang indeed did join the war on Russia’s side.

– What is Ukraine doing?

Ukraine is preparing as though combating North Korea in its territory is inevitable.

An injection of 10,000 North Korean troops, which is what both Ukrainian and South Korean intelligence have claimed, “could significantly destabilise Ukraine’s defence there and greatly accelerate the advancement of Russian forces,” said Glib Voloskyi, an analyst from a Ukrainian think tank, Come Back Alive Initiatives Centre.

Ukraine’s “I Want to Live” project, a hotline encouraging Russian soldiers to surrender, published a video in Korean on Wednesday calling for North Korean soldiers to give up.

“We call for the soldiers of the Korean People’s Army, who were sent to help the Putin regime. You should not die senselessly on someone else’s land.

“There is no need to repeat the fate of hundreds of thousands of Russian soldiers who will never return home.”

– How is the West reacting?

Mr Zelensky told reporters on Monday that the European Union and the US have been cautious in publicly addressing North Korean troops fighting alongside Russia — describing their reactions as “very restrained”.

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South Korea’s vice foreign minister Kim Hong Kyun, right, meets with Russian ambassador to South Korea Georgy Zinoviev at the Foreign Ministry in Seoul, South Korea (South Korea Foreign Ministry/AP)

German and British officials also weighed in, with South Korea hinting that it could support Ukraine with military weapons in the event of North Korea’s confirmed involvement.

“We don’t even know whether we are talking about 1,500 or 12,000, or which kind of soldiers are coming to Russia and to fight where and against,” German Defence Minister Boris Pistorius said.

“It’s a kind of escalation and it shows us a very important, a very important aspect. International conflicts are approaching very rapidly.”

United Kingdom Defence Secretary John Healey said there was “not just a concern about the potential for an escalation of conflict in Europe. There is an indivisible link with security concerns in the Indo-Pacific as well”.

– Why does Russia need North Korea?

North Korea and Russia, both in separate confrontations with the West, have deepened their military cooperation in the past two years.

In June, they signed a defence deal requiring both countries to provide military assistance if the other is attacked.

For analysts, the introduction of troops would be a sign that the war is not going as Russia planned.

North Korea has already sent over 13,000 containers of artillery, missiles and other conventional arms to Russia since August 2023 to replenish its dwindling weapons stockpiles.

Those missiles are being actively used against Ukrainian targets, officials in Kyiv say.