Four years into Russia’s full-scale invasion of Ukraine and one of the war’s stranger subplots may be its most consequential: soldiers from an Asian country with no direct stake in the conflict, and no public declaration of belligerency, are dying by the thousands on European soil, thousands of kilometers from home. 

Since October 2024, North Korea has sent an estimated 15,000 to 20,000 troops to Russia’s Kursk region, and absorbed roughly 6,000 casualties based on the intelligence estimates of South Korea and the United Kingdom. According to Ukrainian officials, North Korea may be asked to contribute tens of thousands more troops. What has Kim Jong Un bought with that blood?

North Korea’s calculus was never primarily about Ukraine, a country with which it has no border, no quarrel, and little history. It was about what Pyongyang could extract from a desperate Russia. By mid-2024, Moscow badly needed manpower and ammunition and had few partners left willing to supply either.

In June 2024, Kim and Russian President Vladimir Putin signed a Comprehensive Strategic Partnership Treaty in Pyongyang that included a mutual defense clause, the first of its kind for North Korea since the Cold War. Troop deployments followed within months. In return, analysts at institutions from the Council on Foreign Relations to Chatham House point to a fairly consistent list of North Korean gains: cash payments estimated in the billions of dollars, food and energy supplies for an economy that chronically struggles to feed and fuel itself, and, most significantly for Pyongyang’s long-term ambitions, technology transfers that would otherwise have been unthinkable. Russia has reportedly supplied North Korea with air defense systems, older but still capable Su-27 and MiG-29 fighters, and, more sensitively, technical assistance connected to satellite launches and naval reactor technology for submarines.

Money and hardware, however, may be less important than what North Korean soldiers are learning. South Korea’s National Intelligence Service has assessed that despite considerable losses, North Korea’s military has gained something it could not otherwise buy: live experience of drone warfare, electronic warfare, and modern combined-arms combat, together with direct exposure to Russian battlefield tactics and equipment. North Korean soldiers rotated home from the front have reportedly gone on to serve as instructors, seeding lessons from Kursk through the wider Korean People’s Army, a pattern documented in detail by 38 North. For a military that has not fought a large-scale war since 1953, that is an intelligence windfall no amount of cash could easily replicate.

There is also a domestic and dynastic logic. Framing the deployment as solidarity with Russia – Kim has publicly praised soldiers for fighting “for the fraternal Russian people” – lets Pyongyang dress a mercenary arrangement in the language of ideological alliance, useful for internal propaganda about North Korea’s rising international stature.

Before 2022, Russia and North Korea were not especially close. Moscow had, at various points, supported U.N. sanctions against Pyongyang’s nuclear and missile programs. The war has inverted that relationship entirely. North Korea has gone from a marginal, sanctioned pariah state to a battlefield-tested security partner that Russia now treats as an equal in a way China never has. The mutual defense treaty, the flow of advanced military technology, and Putin’s own visit to Pyongyang in 2024 all mark a qualitative shift from transactional arms sales to what Foreign Affairs described as a long-term strategic and ideological partnership.

That shift has complicated, rather than strengthened, the informal China-Russia-North Korea alignment that Western officials sometimes describe (misleadingly, most regional specialists argue) as a unified axis. 

Beijing has watched Pyongyang’s deepening entanglement with Moscow with open unease, as detailed in a Foundation for Strategic Research assessment of the evolving triangle. China has no formal say over what Russia transfers to North Korea, and reports of sensitive technology moving from Moscow to Pyongyang without Beijing’s knowledge have reportedly fed distrust between the two communist neighbors. 

Kim, for his part, has gained new leverage over Beijing: with Moscow now willing to treat him as a peer and to backfill North Korea’s economic and military needs, Kim is less dependent on Chinese patronage than at any point in decades, and better positioned to resist Chinese pressure to rein in his nuclear program, a dynamic the Council on Foreign Relations has flagged as a growing headache for Beijing. 

China is wary of jeopardizing its own relationship with Europe, and visibly uncomfortable with a North Korea-Russia partnership it can neither control nor fully endorse. Still, Beijing has responded with something closer to silence than alarm, avoiding direct criticism of either Moscow or Pyongyang. The result, as Modern Diplomacy put it, is less a trilateral alliance than a triangle of powers with overlapping but not identical interests, in which Pyongyang has quietly gained room to maneuver at Beijing’s expense.

Militarily, the record of North Korean troops in Kursk is mixed. In their first months of deployment, North Korean units suffered catastrophic losses. By some estimates, 40 percent of the initial 11,000-strong contingent was killed or too badly wounded to fight within three months. U.S. officials described North Korean assaults on entrenched Ukrainian positions as “human wave tactics” that were, in Washington’s assessment, largely ineffective. Soldiers were used as bait to draw out Ukrainian drone operators, and troops sometimes took their own lives rather than risk capture, a reflection of the harsh consequences reportedly awaiting the families of anyone who surrenders.

Yet the “cannon fodder” framing, embraced early on by Ukrainian and American officials, has been challenged by military analysts who argue it understates what is actually happening. Researchers at RAND have cautioned that dismissing North Korean troops as unsophisticated fanatics risks recycling old stereotypes about Asian communist militaries. Many of the deployed units come from North Korea’s elite special operations Storm Corps – troops that, by multiple Ukrainian frontline accounts, proved highly motivated, resilient under fire, and increasingly adept at countering the first-person-view drones that have come to define this war. Ukrainian intelligence has also reported the arrival of dedicated North Korean drone units and reconnaissance specialists, a more technical role than the infantry-assault image that dominated early coverage.

Materially, the more significant North Korean contribution to Russia’s war effort may not be soldiers at all but ammunition: Ukraine’s military intelligence chief estimated that North Korean-supplied artillery shells and missiles have accounted for roughly half of what Russian forces fire at the front. Troop deployments helped Russia recover Kursk territory that Ukraine had seized in its August 2024 incursion, but North Korean units have so far been confined largely to Russian soil, with reports suggesting Moscow has been reluctant, at least officially, to send them into Ukraine proper. That distinction lets both governments continue denying direct North Korean involvement in the invasion itself, even as evidence of attacks on Ukrainian border communities accumulates.

Whether North Korean troops have changed the trajectory of the war is, in the end, a narrower question than whether the deployment has changed North Korea. On the battlefield, the contribution has been real but bounded: enough manpower and ammunition to matter at the margins in one contested region, not enough to shift the war’s fundamental stalemate. Off the battlefield, the returns for Pyongyang look considerably larger: modernized air defenses, combat-tested doctrine, hard currency, food, and fuel, and a Kremlin now invested in North Korea’s survival and expansion for reasons of its own.

Four years ago, North Korea was a country largely locked out of great power politics, dependent on China and periodically threatened with further isolation over its nuclear program. Today it has a mutual defense treaty with Russia and North Korean soldiers are gaining experience in modern warfare on European battlefields. For a regime that has always measured success in decades rather than news cycles, that may be the trade Kim intended to make all along.