An enemy who entered the battlefield in large groups amidst heavy firing, as if unaware of the dangers of firing from drones and automatic weapons. 'Elite Ghost Soldiers' who chose suicide instead of surrendering. They fought in thousands and were martyred, then it seemed as if they disappeared from the battlefield.
North Korea sent troops to fight alongside Russian forces in an attempt to repel Ukraine's invasion of Moscow territory in late 2024. They had to pay a heavy price for this, out of the 13,000 soldiers deployed, about 3,000 were killed in action.
Eventually, they changed their strategy and, together with Russia, drove Ukrainian forces from the Kursk region. From a combat perspective, not much has been heard about them since then, but according to Ukrainian President Volodymyr Zelensky, North Korean forces and their weapons may soon make a dramatic comeback in the Ukraine war.
Last month, Zelensky warned that up to 50,000 North Korean troops would be deployed to Russia, a revision of his earlier estimate of 30,000 troops. He called on South Korea to provide help for the air defense of his country.
But why would North Korea send more troops to fight for Russia despite such heavy losses, and what happened to its initially sent troops?
"They are still there. They are protecting Russian territory from any retaliatory attack from Ukraine. We believe the engineer corps or some personnel may be in the (Russian-occupied) Donbass region, but they are not combat troops," said Dr. Yang Uk, a researcher at the Asan Institute for Policy Studies, Center for Foreign Policy and National Security, based in Seoul, South Korea's capital.
The Main Intelligence Directorate (HUR) of the Ukrainian Defense Ministry estimates that 8,500 North Korean soldiers are still present on Russian territory.
These troops are organized into four brigades, which act as part of the "North" military group and are tasked with protecting the Russian Federation border in the Kursk region from Ukrainian incursions.
The HUR said in a statement to the BBC: "They do not participate in active combat operations. Korean People's Army units have not been seen in the temporarily occupied territories of Ukraine."
For North Korean leader Kim Jong Un, the military deployment to Kursk was a risky move, the largest combat force ever sent overseas. (In 1973, North Korea sent 1,500 military personnel and trainers to Egypt during the Yom Kippur War with Israel, and in the late 1960s, an estimated 87 North Korean pilots fought for North Vietnamese forces against American forces).
And despite the bloodshed, it proved to be a risky move that was successful, bringing countless benefits to this isolated and impoverished country and bringing unprecedented change to its economic and military situation. And this could become a model for even deeper military cooperation in the future.
"North Koreans now know what modern warfare is," Yang said.
The soldiers sent to fight in Russia were from the Storm Corps, an elite unit of the North Korean armed forces. Isolated, dictatorial North Korea is a militarized and fanatically ideological state.
Initially, neither Russia nor North Korea acknowledged their presence. Ukrainian forces first clashed with them in November 2024, and the first surviving North Korean prisoners of war were not captured until January the following year.
Russia did not first acknowledge his role until April 2025, but Valery Gerasimov, chief of the General Staff of the Russian Armed Forces, described his "heroism" on the battlefield.
Yang further said, "North Korean soldiers are very brave, especially those in the 'Storm Corps'. They are willing to sacrifice their lives for their country. But the problem is that zeal does not mean efficient combat skills... They suffered heavy losses at the beginning of the Kursk campaign, but they also learned lessons from modern drone warfare."
"Sultan", a soldier in Ukraine's 95th Air Assault Brigade, described North Korean soldiers as "cannon fodder". He faced these same soldiers in the Battle of Kursk in late 2024.
"They would start with a large assault group, then send 15-20 more soldiers to the same location, and then more. North Korean soldiers operated in a different way. They were on the move all the time. This gave them some advantage, but not a decisive advantage," he recalled recently in Kiev.
He said coordination between them and their Russian allies was poor and their troops lacked necessary equipment.
After the battle, the Sultan and his companions would search the enemy's bodies for documents and intelligence. They found personal belongings, identity cards and equipment on the dead bodies of the Russians. "But when we specifically searched the North Korean soldiers, we only found ammunition. We also checked all their small pockets - no documents, nothing," he said.
Other Ukrainian soldiers reported that North Korean soldiers lacked body armour, winter clothing and helmets.
In a heartbreaking video of the Ukrainian attack, a wounded North Korean soldier lies on his stomach on snow-covered ground in a forested area. As Ukrainian soldiers approach, he pops a grenade under his chin; Before doing this, in his last words he calls the name of his leader Kim Jong Un.
In April 2025, at a memorial service held at the Museum of Foreign Military Operations in Pyongyang, Kim praised the heroes who chose suicide rather than being captured.
In a speech to family members in the presence of Russian Defense Minister Andrey Belousov, he said he was "a hero who, in order to protect great honour, without hesitation chose the path of blowing himself up, that is, a suicide attack."
Although North Korea has never officially acknowledged the death toll in the Kursk operation, an analysis of the memorial site by BBC Korea estimates that 2,300 soldiers died fighting for Russia.
According to Ukraine's intelligence agency, HUR, the death toll is 3,000 and the number of injured is 1,500.
But combat experience aside, why did North Korea sacrifice so many of its best soldiers in a foreign war?
an unexpected financial gain
According to Lim Soo-ho, senior researcher at the Seoul-based National Security Strategy Institute, this deployment has proved to be a much-awaited economic benefit and a geopolitical victory for the country.
He estimates that this poor country has benefited about $10 billion from arms sales and military deployment to Russia.
"North Korea's annual GDP is estimated at about $30 billion (22 billion pounds). That means they earned a third of a year's GDP in two and a half years through arms exports and military deployments, which is very significant for a small economy like North Korea," he told me.
In exchange for its manpower, North Korea gets food, oil and foreign currency. China says it abides by sanctions against North Korea, while Russia does not.
But more importantly, cooperation with Russia has replaced North Korea's long-term dependence on China.
In September last year, Kim Jong Un was able to stand shoulder to shoulder with Chinese leader Xi Jinping and Russian President Vladimir Putin in Beijing, this was the first public meeting of the three. Not equal status, but now they are no longer dependent only on China.
Lim said this is important, "this is a big change in geopolitics".
"Whenever the situation became difficult due to isolation, North Korea would first try to normalize relations with South Korea, Japan, or especially the United States; this has been the style of diplomacy on the Korean Peninsula. But now relations with Russia have deepened, and Kim Jong Un believes that the world is in the era of a new Cold War and multipolar system."
What began as an agreement with Russia based on economic and military needs now appears to be turning into a much deeper and longer-lasting relationship. At the 9th Party Congress of the Korean Workers' Party this year, Kim Jong Un appeared confident and cited achievements that his grandfather Kim Il Sung and father Kim Jong Il were never able to achieve.
But there are dangers ahead. So far, no North Korean soldiers have fought in Ukraine or in Russian-occupied Ukrainian territory. If they do, it would have diplomatic consequences, especially for South Korea, which is an ally of Ukraine, although it has so far provided only "non-lethal" aid.
President Zelensky has emphasized this and is demanding from Seoul to provide advanced military hardware, including air defense systems. He said that since June, preparations have been going on in the Voronezh area of Russia to welcome a new batch of North Korean soldiers and claimed that North Korea is preparing to send more ballistic weapons to Russia.
In a presidential speech in July, he said, "Russia is helping North Korea learn modern warfare, improve its weapons, and gain real combat experience. This poses a threat to all countries in Asia that come within the range of North Korean missiles."
Only two North Korean soldiers were captured alive in the fighting with the Ukrainian army. This number is very low, especially when 11,000 to 14,000 soldiers took part in the Kursk campaign. (According to South Korea's National Intelligence Service, another soldier was captured alive but died of injuries sustained in the battle).
Unlike their comrades who chose suicide rather than being captured, neither of them intended to be captured alive.
"For Joseon (North Korean) soldiers, becoming a prisoner of war is a crime. It is not an option. We cannot become prisoners of war," one of the captives told a South Korean MBC documentary crew interviewed in a Ukrainian prison.
Baek Pyong-gang (this is not his real name) was injured in the drone attack and lay there for four days, after which he was captured. They were forced to surrender by deception, as they mistook the Ukrainian soldiers for their Russian allies.
The other prisoner, Lee Kang-eun (a pseudonym), told journalist Kim Young-mi that he felt guilty about his survival. Nearly unconscious, Ukrainian soldiers found him on the battlefield, with severe injuries to his arms and jaw.
He told, "I did not have any grenade or knife to commit suicide (take my life)."
He described many of his comrades killed in drone strikes in the early stages of the war. He said that the smell of blood was spread in the battlefield.
Neither of them wants to return to North Korea. Lee said he believed his family members would be "exterminated" as punishment for his arrest. Both have expressed their desire to be sent to South Korea and Seoul is ready to accept them.
But Ukraine, which is still bent on pressing South Korea for military assistance, has not committed to handing them over to South Korean authorities. Ukraine has said it will abide by international human rights obligations that prevent the forced return of prisoners of war.
For Russia and North Korea, it is a mutually beneficial relationship, an alliance that has a price. Ultimately, North Korea will continue to send troops to fight in Russia's wars, but only as long as it is profitable to do so.
