To achieve peace in Ukraine, the incoming Trump administration will have to turn off Russia’s most active ally — North Korea. Last year, after watching Russia falter in Europe’s largest war since World War II, North Korea’s leader, Kim Jong-un, jumped at the chance to earn combat experience for his military and hard currency for his vast military stocks.

Russia this year has relied on North Korea for half of its artillery shells fired in Ukraine. After three years of war, Russia has lost almost half of its 2,000 tracked howitzers, largely due to gun barrel fatigue. Recently, though, videos have shown dozens of North Korean-made M1989 howitzers rumbling across Russia on rail cars. Designed to shell Seoul, these guns fire 170-millimeter shells, a caliber only produced in North Korea. This means Russia will rely even more on North Korea for ammunition.

On the personnel front, President Zelensky of Ukraine said Monday that, after three weeks of combat in Russia’s Kursk region, 3,000 North Koreans have been killed or wounded. South Korea’s estimate is 1,100. Given the Western estimate of 11,000 North Korean soldiers in Kursk, this means a casualty rate of 10 percent to 27 percent for the month of December.

For most militaries, this would be appallingly high. Yet South Korea’s joint chiefs of staff reported Monday that North Korea is preparing to send more soldiers to Russia. By Western standards, North Korea has bottomless reserves: a standing army of 1.3 million.

South Korea’s military also says Pyongyang is ramping up production of drones and ballistic missiles with an eye to exporting to Russia. During nearly three years of war, North Korea’s arms exports to Russia earned the country up to $5.5 billion, according to a study by a researcher at Seoul’s Hankuk University of Foreign Studies, Olena Guseinova. In 2025, North Korea could earn $500 million for supplying troops. This adds up to almost a quarter of North Korea’s gross domestic product.

Russia’s outsourcing of war to an impoverished neighbor 4,000 miles from Moscow portends a new, global security threat for America, a Rand Corporation strategist, Raphael S. Cohen, writes in a new Foreign Policy essay: “China and North Korea Throw U.S. War Plans Out the Window.” In a working alliance rarely seen since the Cold War, America’s adversaries are moving beyond using UN speeches to show support. Instead, they are arming each other.

“For the first time, the United States’ adversaries are willing to come to the direct military aid of one another, even on the other side of the globe,” Mr. Cohen writes, citing North Korea and Iran providing military aid to Russia, and Chinese ships in the Baltic cutting internet cables connecting Western allies. “Call it an ‘axis of aggressors,’ an ‘unholy alliance,’ a new ‘axis of evil,’ or something else altogether—the fact remains that military ties among China, Russia, Iran, and North Korea are deepening.”

“Pacts and promises are one thing; direct involvement in two ongoing wars in Europe—a hot one and a hybrid one—is quite another,” he writes. “China and North Korea have now crossed that Rubicon.”

For Russia, the use of North Korean soldiers is part of a race to conquer as much ground as possible before President-elect Trump’s inauguration on January 20. With Ukraine’s army largely in a defensive crouch, Russia throws wave after wave of soldiers against Ukrainian positions. While the war is largely off the front pages, the fighting is in its bloodiest phase since President Putin launched the full-bore invasion, in February 2022.

Last Friday, Russia had 2,200 soldiers killed or wounded — the highest casualty rate for a single day in the war, according to Ukraine’s general staff. The other two times when Russia lost more than 2,000 men in one day were November 11 and 29. As of Monday, Russia has had 777,720 soldiers killed or seriously injured. Ukrainian casualties are estimated to be a third of this number.

In the field, Ukrainian military statistics indicate, Russia has lost almost 10,000 tanks, almost 20,000 armored personnel carriers, and 21,000 artillery systems. Russia’s territorial gains have been minimal and pyrrhic. On Monday, the Russian defense minister, Andrei Belousov, boasted that Russian forces are capturing 11.5 square miles of territory a day. Last Friday, that would have cost almost 200 soldiers per square mile.Given the country’s size – slightly smaller than Texas – it would take Russia 55 years to conquer Ukraine.

By January 20, Russia’s casualty toll is expected to hit 800,000. Both sides believe that the new Trump administration will try to impose an immediate ceasefire as a first step toward talks leading to a Korea-style armistice. A big challenge would be geography: On the Korean peninsula, the Demilitarized Zone is 160 miles long. In Ukraine, today’s front line is 727 miles long.

Would North Korea demand a seat at the negotiating table? Last month, the country’s foreign minister, Choe Son Hui, said during a visit to Moscow: “North Korea assures Russia that it will always be with the Russian comrades until the day of victory.”

Officially, both sides deny that North Korean soldiers are actually fighting in the war. Pyongyang has dismissed the reports as “fake news.” Yet today’s Internet is littered with photos of terrified North Korean soldiers peering up at Ukrainian military drones.

Russia also seeks to minimize the role of North Korean fighters. Reports say they have been issued fake IDs calling them Buryats, a Russian Asian group. Most of the North Koreans are fighting in a 150-square-mile salient of Russia’s Kursk region that Ukrainian troops have occupied since August 6. Mr. Putin evidently does not want to draw attention to the fact that he has not been able to muster enough Russian men to liberate their own land. The fighting is so tough that Mr. Putin refuses to set a target date for expelling the Ukrainian invaders.

When a video emerged of a Russian soldier standing over a corpse with a burning head, President Zelensky charged on his X account that Russian soldiers are burning the faces of the North Korean dead to hide their presence.

“After first combats with our warriors, Russians are trying … to literally burn the faces of North Korean soldiers killed in battle,” Ukraine’s president wrote. “There is not a single reason for North Koreans to fight and die for Putin. And even after they do, Russia has only humiliation for them.”

Other drone videos show the bodies of as many as 20 North Korean soldiers lined up in the snow awaiting removal. Last week, Ukraine’s state service posted audio of what it said was an intercepted phone call from a Russian nurse saying more than 200 wounded North Koreans are being treated at her hospital near Moscow. The woman tells her husband: “A train came in yesterday, around 100 people, today 120 more, that’s 200. God only knows how many more there are.”

High casualty rates for the North Korean soldiers seems to reflect their unfamiliarity with warfare in open steppes and with killer drones. One drone video shows a line of soldiers trying to advance in broad daylight across an open field. Their olive green uniforms stand out against the white snow.

If the North Korean soldiers do succeed in expelling the Ukrainians from Russian territory, this might allow Mr. Putin to declare “victory” and accept an armistice along current lines. Already, Moscow’s attitudes are shifting. On Monday, a Kremlin foreign policy adviser, Yuri Ushakov, predicted that North Korean soldiers would be invited to take part in next May’s parade across Moscow’s Red Square. By goose-stepping across the cobblestones, they would join commemorations of the Soviet victory in World War II.