When Russian President Vladimir Putin traveled to Pyongyang in June 2024, his first visit to North Korea in nearly a quarter century, the optics were striking. Russian flags and portraits of Putin adorned the capital, where he was treated to an elaborate welcome ceremony with a military honor guard and groups of balloon-toting children. But this was to be expected; such pageantry is a hallmark of North Korean politics. Less anticipated was the substance of Putin’s subsequent meeting with North Korean leader Kim Jong Un. The Treaty on Comprehensive Strategic Partnership the two men signed that day formalized a relationship that had been quietly taking shape since Russia’s full-scale invasion of Ukraine in 2022: a military alliance between two nuclear-armed pariah states. By October 2024, around 11,000 North Korean troops had been deployed to Russia, primarily in the Kursk region along Ukraine’s northeastern border, to support Russian combat operations. By late April 2025, South Korean intelligence assessments put Pyongyang’s troop presence at around 15,000, and at least half that number remain deployed.
The partnership has made a significant difference in Russia’s war effort. North Korea’s conventional military is often written off as small and underdeveloped, but the country has become a key supplier of artillery ammunition, select missiles, and manpower to Russia. In February 2025, Ukraine’s military intelligence chief publicly claimed that North Korea was providing about half the ammunition Russia was using at the front. Based on Ukrainian military intelligence estimates from November 2025, North Korea has supplied Russian forces with around 6.5 million artillery rounds since 2023 and with sophisticated long-range self-propelled artillery systems and multiple launch rocket systems since late 2024.
The partnership is making the Korean Peninsula a more dangerous place, too. Not only has North Korea gained military capabilities from Russia and experience from fighting in its war, but deepening economic and diplomatic ties between the two countries have relieved some of the pressure that for decades has kept North Korea subordinate to China. Now, with more confidence in its conventional military and in a position to play two great-power patrons off each other, North Korea faces fewer constraints than ever before. And should Pyongyang choose aggression against its southern neighbor, the resulting war would likely not be limited to a fight between North Korea and a U.S.-backed South Korea but draw in Russia and China, as well.
U.S. policymakers have been hoping to offload some of the responsibility for maintaining peace on the Korean Peninsula to Seoul. But Washington has missed the fact that this task has fundamentally changed. Deterring Pyongyang now means deterring Beijing and Moscow, too, and South Korea, as capable as it is, cannot do this alone. For Washington to step back at this perilous moment would raise the risk of war even further and push the United States into the very situation it should want to avoid: embroilment in a conflict with North Korea, China, and Russia—nuclear powers all.
BASIC TRAINING
The Korean Peninsula has been one of the world’s most dangerous flash points since North Korea, with the support of communist China and the Soviet Union, invaded South Korea in 1950. The United States led a 16-country United Nations force to defend South Korea; China intervened a few months later on behalf of North Korea. The fighting lasted three years, stopping only after two years of tortuous, on-and-off negotiations. The resulting armistice created the demilitarized zone (DMZ), which now serves as the border between North and South Korea. Because the two countries never signed a peace treaty, they are technically still at war. The possibility of a second North Korean invasion or regime collapse in Pyongyang has driven U.S. and South Korean military planning ever since.
Over the past seven decades, direct clashes, provocations, and close calls have repeatedly tested the armistice. In 1968, North Korea sent a 31-man commando unit to Seoul in an audacious attempt to assassinate South Korean President Park Chung-hee, and days later, its navy seized the USS Pueblo, an American intelligence vessel. In the 1970s, South Korean soldiers discovered that secret tunnels had been dug under the DMZ, and North Korean soldiers killed two American officers in the zone’s Joint Security Area, an incident that nearly triggered open conflict. Confrontations in the Yellow Sea led to deadly clashes in 1999, in 2002, and, most dramatically, in 2010, when North Korea torpedoed the South Korean corvette Cheonan, killing 46 sailors, and then shelled Yeonpyeong Island, wounding and killing both soldiers and civilians.
The danger on the peninsula gained a nuclear dimension in the 1990s, when North Korea announced its plan to withdraw from the Nuclear Nonproliferation Treaty. Negotiations with the United States delayed Pyongyang’s formal withdrawal until 2003, but afterward North Korea quickly advanced its weapons development, conducting six nuclear tests between 2006 and 2017. Pyongyang’s intercontinental ballistic missile test in 2017, meanwhile, demonstrated for the first time a potential capability to reach the continental United States—a threat it has since reinforced with additional tests and technological development. After a brief diplomatic opening in 2018, when Kim joined meetings with both South Korean President Moon Jae-in and U.S. President Donald Trump, ended with no lasting agreements, North Korea accelerated its missile testing. It has continued to expand its nuclear arsenal in the years since. As Kim declared in a speech in March, the country now possesses “the power to pose a threat if necessary.”
North Korea faces fewer constraints than ever before.
Today, the lessons North Korea is learning in Ukraine are also strengthening its capacity to launch limited attacks, which increases the likelihood that a clash could escalate to general war. To be sure, a hypothetical conflict on the Korean Peninsula would not look quite the same as the war in Ukraine, so Pyongyang’s on-the-ground experience would not give it a decisive edge. North Korea would face a more formidable opponent than the one Russia faced when it first invaded Ukraine: the South Korean military, with half a million troops and modern high-tech equipment, has been planning, exercising, and stockpiling in preparation for a North Korean attack for more than 70 years, and it would likely be joined by the United States in combat, given that around 28,500 U.S. troops are stationed in South Korea. Yet North Korea would have advantages, too. It could put Seoul at risk without advancing first; the city and its more than ten million inhabitants are only about 30 miles from the DMZ, well within range of North Korea’s nearly 6,000 artillery systems. And at less than 160 miles, the DMZ line running across the Korean Peninsula would be far shorter than the 750-mile frontline today in Ukraine—favoring North Korea at the outset by allowing it to concentrate its forces and deliver a powerful opening salvo.
After a war got underway, North Korea, like Russia, would rely on massed artillery to suppress South Korean and U.S. defenses, disrupt command and control, and strike major military targets around Seoul. It would be unlikely to gain air superiority, so its ground forces would have to adopt dispersal and concealment methods to avoid air attacks. And it would likely need to use its short-range missiles in the same way Russia is using these North Korean weapons today, to strike logistics nodes, command posts, air defense systems, and infrastructure. The thousands of North Korean troops sent to Russia—the first large-scale deployment of North Korean forces to a foreign theater since the Cold War—are learning how to do all of this. This cohort has suffered significant casualties; as of February, South Korean intelligence estimated that about 6,000 soldiers, more than a third of the deployment, had been killed or wounded. Yet the North Korean troops are also developing greater skill with modern weapons and now operate surveillance drones, clear mines, and execute artillery strikes for Russia. Soldiers returning to North Korea are practiced in the combined arms, drone, and electronic warfare that define the modern battlefield—experience that no training exercise can replicate.
Pyongyang seems keen to institutionalize the lessons these soldiers have learned. Last May, the North Korean army held an officer training session in which returnees shared insights from the Russian frontlines. According to Ukrainian military intelligence, many of the roughly 3,000 North Korean soldiers who have gone home now serve as military instructors. The war in Ukraine has also provided North Korea with a live operational environment where it can test its weapons and equipment and send real-time performance data back to engineers in Pyongyang. The results are visible. The same North Korean short-range ballistic missiles that were malfunctioning at high rates in early 2024 and missing their targets by up to two miles were far more accurate by early 2025, typically striking within 55 to 110 yards of their intended targets.
North Korea also seems to have secured technology transfers in exchange for helping Russia in Ukraine—support that could help Pyongyang field the capabilities it would need to fight a potential war on the Korean Peninsula. Advanced satellite technology from Russia, for instance, would give Pyongyang better surveillance and targeting data than it has now and, over time, make its missile forces harder to hide and easier to use effectively. Kim approved plans to develop technologies used to attack enemy satellites at a party congress in February; North Korea’s 2024 agreement with Russia also identified space as an area for bilateral cooperation. In drawing from Russia’s experience with antisatellite systems and electronic warfare, North Korea could lower its own technical barriers to developing the means to disrupt an adversary’s space-based capabilities.
International monitors report that since late 2024, Russia has provided North Korea with modern air defense systems suitable for guarding against drones, cruise missiles, and precision munitions. It has also provided advanced electronic jamming gear and operational know-how that could help Pyongyang degrade South Korean and U.S. communications, jam GPS, and make it harder for drones to operate during a conflict. According to South Korean press reports citing anonymous government officials, in the first half of 2025 Russia provided North Korea with key parts for a nuclear-powered submarine, possibly including a reactor, a turbine, and a cooling system. If the reports were accurate, it still does not mean that North Korea has an operational nuclear-powered, missile-capable submarine, but that would certainly speed up the development process.
These gains together may not turn the military balance on the peninsula in North Korea’s favor, but they are enough to matter at the start of a crisis. A North Korean force that is better at dispersal, concealment, drone use, and electronic warfare would be harder for South Korea and the United States to suppress quickly. That knowledge could make Kim more confident in carrying out limited escalation or a coercive attack to achieve a discrete goal, such as economic concessions or recognition of the legitimacy of his regime or his nuclear program.
It is also possible that this military progress will embolden Kim to take more decisive action. Although most observers believe that he is primarily focused on regime survival, statements he made in 2023 and 2024 describing South Korea as a “hostile state” and the “principal enemy” of North Korea suggest that Pyongyang might be recalculating. If Kim has come to believe that a window of opportunity has opened—particularly if he doubts the U.S. commitment to South Korea—his recent military buildup might be intended for offensive purposes. And even if North Korea still does not seek all-out war, any intentional or unintentional provocation could become harder to contain as Pyongyang becomes more sure of its own capabilities and the support it can secure from Russia as well as China.
TWO PATRONS ARE BETTER THAN ONE
The likelihood that an external force will stay Kim’s hand in a crisis is declining because close ties with Russia give North Korea strategic options it didn’t have before. For decades, the Kim regime’s sole dependence on China constrained its decision-making. Pyongyang has relied on Beijing for the vast majority of its energy, food, and trade; in 1993, China supplied 77 percent of North Korea’s fuel imports and 68 percent of its food imports. During the famine that ravaged North Korea in the second half of the 1990s, killing anywhere from half a million to more than three million people, China sent hundreds of thousands of tons in emergency grain shipments each year. China—and South Korea—continued to send food aid to North Korea in the following years; in 2005 alone, they together provided nearly one million tons. North Korea’s access to foreign trade, meanwhile, comes overwhelmingly through China. In 2010, China accounted for over 80 percent of North Korea’s total trade, a figure that climbed to roughly 95 percent or more after UN sanctions on North Korea tightened in 2016–17 and has remained at roughly the same level in the years since.
Throughout this time, Beijing has been wary of using its leverage to push for drastic political change in North Korea. It preferred to wait for gradual economic reforms that could help stabilize the regime. Beijing has also been concerned that too much pressure on Pyongyang could result in disaster in the form of regime collapse or military aggression. Washington criticized this approach, particularly Beijing’s reluctance to force Pyongyang to give up its nuclear program. But China’s interests also overlapped in important ways with those of Washington and its allies. Beijing supported UN sanctions on North Korea and encouraged Pyongyang to come to the negotiating table, facilitating the six-party nuclear talks that China and North Korea began in 2003 with Japan, Russia, South Korea, and the United States. Before Pyongyang quit in 2009, the talks yielded a set of agreements in 2007 requiring North Korea to shut down and seal its Yongbyon nuclear facilities and allow the International Atomic Energy Agency to monitor the site in exchange for substantial shipments of heavy fuel oil from the other countries.
Russia’s relationship with North Korea today is different. From 2006 to 2017, Moscow voted in favor of every major UN sanctions resolution against North Korea, but now it is actively undermining the international restraints it helped construct. Most damaging, in March 2024, Russia used its UN Security Council veto to block the renewal of the mandate of a UN monitoring committee that documented violations of North Korean sanctions—violations that included Russia’s own procurement of North Korean weapons for use in Ukraine. In Security Council debates, Russian diplomats have often parroted Pyongyang’s language, describing North Korea’s nuclear and ballistic missile development not as a violation of international law but as a predictable response to American hostility and efforts to “strangle” the North Korean regime. Since 2021, Russia has also submitted resolutions calling for sanctions to be eased or reversed, and since 2022 it has used the threat of its veto to water down or kill Security Council statements condemning North Korean missile tests.
Deterring Pyongyang now means deterring Beijing and Moscow, too.
Although North Korea remains economically dependent on China, Russia has been offering the regime a financial lifeline since the signing of the June 2024 mutual defense agreement. Russia’s official bilateral trade with North Korea reached a record $34 million that year—a small amount compared with China’s roughly $2 billion in annual trade with the country but nearly a tenfold increase from North Korean–Russian trade in 2022. Moscow also unfroze $9 million in North Korean assets held in Russian financial institutions in 2024, granting Pyongyang access to the international banking system for the first time in years. Russian ships have been openly flouting sanctions as they ferry munitions from North Korea and deliver much-needed oil and other fuel in exchange.
The relationship between North Korea and Russia threatens to diminish China’s influence, and Beijing has responded by working harder to ingratiate itself with Pyongyang. China has run this play before, understanding that its leverage depends on remaining indispensable to all the relevant players on the Korean Peninsula: in the spring of 2018, days after the announcement that Trump and Kim would meet in person for direct negotiations, Chinese leader Xi Jinping tried to create an intermediary role for China by welcoming Kim to Beijing on his first foreign trip since becoming leader in 2011. And in a break from its previous record, China began to join Russia in pushing for more lenient treatment of North Korea at the UN Security Council.
Now China is reacting to an uptick in North Korean–Russian engagement in a similar way. Between 2023 and 2025, senior Chinese and North Korean officials met eight times, compared with Russian and North Korean officials’ 25 times. But the pace of China’s meetings picked up in late 2025. Kim traveled to Beijing in September and held a private meeting with Xi, the first time the two leaders had sat down together in six years. The following month, Chinese Premier Li Qiang made a reciprocal trip to Pyongyang, becoming the most senior Chinese official to visit North Korea since 2019. Both countries issued statements calling for “strengthened strategic coordination” and “deepened practical cooperation,” suggesting that Beijing is keen to reassert its position as Pyongyang’s primary patron. Trade between the two countries has rebounded to a level close to what it was before the COVID-19 pandemic, and ground routes across their shared border that were closed in 2020 have opened back up. China’s renewed interest gives North Korea more diplomatic and economic room to maneuver. If Beijing is working hard to stay indispensable to Pyongyang, it will hesitate to undermine that effort—and risk pushing North Korea even closer to Russia—by pressuring the Kim regime.
THAT ESCALATED QUICKLY
The problem with growing North Korean–Russian alignment is not just that it has eased critical constraints on a potential conflict on the Korean Peninsula. It has also ensured that any such war would be more dangerous. It has been clear for decades that China would intervene militarily in any major conflict between North Korea and South Korea—not to rescue Kim’s regime, but to advance its own interests. If the collapse or defeat of the Kim regime were imminent, China would move quickly to control North Korean territory, secure nuclear facilities, and guide the postwar political settlement. Russia, on the other hand, has neither the geographic proximity nor the force posture to compete with China’s ability to move troops rapidly across the North Korean border, and to date it has shown no intention to contest China’s postwar influence.
Beijing would prefer to keep Moscow’s involvement to a minimum. But Russia now has new commitments to defend North Korea, and China cannot stop it from living up to them. Russian involvement, moreover, would make it more difficult for China to protect its own interests in maintaining stability and preserving its leverage over North Korea. Moscow would want a say in when and how to de-escalate, as well as in any political agreements made after a conflict—and its preferences might not align with Beijing’s. In general, Russia demonstrates a greater tolerance for risk and global disorder than China does. And in North Korea in particular, Russia is less exposed to a potential refugee crisis and is less invested in the future of East Asia than China is.
In this uneasy three-country coalition, North Korea would be in a prime position to ask both China and Russia to deploy troops in support of its war efforts, because neither country would want to give up the opportunity to shape a conflict that could directly affect its security interests. Even if these troops were not fighting alongside the North Koreans but stationed elsewhere on the peninsula, their mere presence would increase the risk of escalation for South Korea and its allies.
With North Korea drawing support from both Russia and China, South Korea would find it difficult to dominate a conventional war. Pyongyang on its own has an estimated 1.3 million active military personnel, in addition to around 600,000 army reservists and roughly 5.7 million paramilitary reservists. South Korea, in contrast, has an active-duty force of around 450,000 troops, a number that is shrinking: the size of the force fell by roughly 20 percent between 2019 and 2025, primarily because of demographic decline. Seoul’s well-trained, well-equipped army, with its strong command and control and integration with U.S. forces, has long held a qualitative edge over Pyongyang’s numerically larger military, and it might be able to offset its manpower declines with even better training and readiness, and affordable, scalable technologies such as drones, cyberweapons, and artificial-intelligence-enabled autonomous systems. But Russian and Chinese technologies, know-how, and production capabilities could erode South Korean advantages. With Russia and China backstopping North Korean production and helping with system integration, their combined defense industrial base could soon overwhelm South Korea’s. They could even outmatch South Korea’s backstop, the United States, which faces significant stockpile and arms production constraints of its own.
A tighter conventional fight and the possibility of direct Chinese or Russian involvement would make a war on the peninsula not just harder to win but also harder to end. The conflict could drag on for months as outside powers replenished munitions and jockeyed to shape the political outcome. A resolution acceptable to all parties could be difficult to find, too, if North Korea tried to prolong the process by playing China and Russia off each other. The war could also widen if North Korea struck the bases and ports in Japan and Guam that U.S. reinforcements would use to enter the theater or if Chinese troops went into North Korea to secure border areas, raising the risks of direct clashes with U.S. and South Korean forces. And the danger of nuclear escalation would rise if allied operations threatened Pyongyang’s leadership, command-and-control system, or nuclear forces. North Korea’s 2022 nuclear law allows nuclear use in response to attacks on those targets, and the regime would have an incentive to use its nuclear weapons early rather than risk losing them before it can act.
THREE-PARTY DETERRENCE
North Korea has not been a priority for Washington lately. The second Trump administration’s attention has been firmly fixed on conflicts in Europe, Latin America, and the Middle East over the past year, and its 2025 National Security Strategy did not even mention North Korea. Its 2026 National Defense Strategy suggests that South Korea ought to take “primary responsibility for deterring North Korea with critical but more limited U.S. support.” But Washington cannot simply leave this responsibility to Seoul. The task today is no longer just deterring North Korea but deterring a Korean conflict that could draw in China and Russia together. Even the United States could not win a war against that set of countries by itself. China and Russia combined have more ships and submarines, military personnel, and tanks than the United States. China alone has surpassed the United States in manufacturing output, an advantage that becomes decisive in a prolonged war. Were the United States to end up in a war on the Korean Peninsula while engaged in a great-power conflict elsewhere, such as a war over Taiwan or in Europe, the two-front fight would stretch its forces, strain its logistics, and potentially compel Washington to withdraw from at least one theater. Avoiding that scenario requires U.S. commitment now. A robust and enduring American military presence raises the risks and costs of a major war for China and Russia, which makes it less likely that either of them would gamble on supporting North Korean aggression in the expectation that they could manage the fallout.
To act as though the United States no longer needs to contribute to deterrence of North Korean aggression would be to make the same mistake that U.S. Secretary of State Dean Acheson did in 1950, when he gave a speech in which he left the Korean Peninsula out of his description of the U.S. defense perimeter in Asia. This gave Soviet Premier Joseph Stalin and Chinese leader Mao Zedong the impression that they could back a North Korean invasion of South Korea without risking an all-out war against the West. Today, overzealous U.S. attempts to shift the burden of peninsular defense to Seoul could again signal to Moscow and Beijing that what happens on the Korean Peninsula is not of great interest to Washington, increasing the likelihood of a war there.
There are steps the United States can take to demonstrate that it is still serious about the North Korean threat. The Trump administration must reiterate the United States’ commitment to defend South Korea if the country is attacked, including a pledge to respond to an adversary’s use of nuclear weapons against South Korea with an American nuclear counterattack. Using such language has long been standard U.S. diplomatic practice, and its omission from the current administration’s official statements is glaring. Washington must also welcome Seoul’s increased defense spending—South Korea pledged late last year to raise its defense budget to around 3.5 percent of GDP as soon as possible—and continue to support the eventual transfer of operational control in wartime to a South Korean command. This would expand Seoul’s role in combined operational planning and in crisis decisions about how much military danger and escalation risk the alliance is prepared to accept, although ultimate command authority over U.S. forces would remain in American hands, and major decisions about military missions would be made jointly by Seoul and Washington.
Together, these moves would strengthen deterrence by making the U.S.–South Korean alliance more capable and more credible. South Korea would bring more resources and assume greater operational responsibility, and the assurance of sustained U.S. support would disabuse any aggressor of the idea that South Korea might be fighting alone.
Strengthening U.S. support for South Korea can help advance other American security objectives in Asia, too. Washington should deploy more assets to the peninsula, but it should also seek Seoul’s agreement that U.S. assets can be used elsewhere if another military conflict breaks out in the region, including a Chinese attack on Taiwan. For now, Washington’s options are shaped by a 2006 joint statement in which it agreed to respect South Korea’s position that U.S. forces in the country should not be drawn into a regional conflict “against the will of the Korean people”; that understanding will need to be updated with more thorough contingency planning. Seoul, meanwhile, already recognizes the need to strengthen its own defense: in a social media post in late January, South Korean President Lee Jae-myung wrote that “it would be unacceptable” for his country, “which spends 1.4 times more on national defense than North Korea’s gross domestic product, to be unable to protect itself.” With higher South Korean defense spending and closer cooperation with the United States on shipbuilding, naval maintenance, and other defense industrial projects, South Korea could become a major arms exporter and munitions producer—which would also make Seoul a genuine strategic asset for Washington.
For now, however, there are signs that the U.S.–South Korean alliance is on shaky ground. The Trump administration has not clarified what it means by providing “critical but more limited U.S. support” to South Korea, and the uncertainty about what Seoul can expect and under what conditions could create a schism in the relationship. Cracks are already beginning to show. In a February National Assembly session, Prime Minister Kim Min-seok fielded harsh criticism from an opposition lawmaker who asserted that the government’s negotiations with Washington had failed to protect South Korea from steep U.S. tariffs. The same month, South Korea declined to participate in a proposed trilateral air exercise with Japan. And later, when a U.S. training mission over the Yellow Sea (between China and the Korean Peninsula) prompted the Chinese military to dispatch its own fighter jets, South Korean officials issued complaints to the U.S. commander—but not to China.
If the United States does not take the necessary steps to deter North Korea and reassure South Korea, the results could be catastrophic. War between the two neighbors would become more likely and, given the high probability of Chinese and Russian involvement, could expand beyond the peninsula. Uncertainty about the division of responsibilities between Washington and Seoul could reduce the effectiveness of any combined response during a crisis. In the meantime, if South Korea grows concerned about the possibility of war and skeptical of the United States’ commitment to its defense, it could be driven to take drastic measures that would pull it out of Washington’s orbit. It would be rational, for example, for Seoul to court Beijing and even give up its relationship with the United States in return for a guarantee that China would hold back both North Korea and Russia. At the moment, such a dramatic reversal would run up against South Korean public opinion. A 2025 poll by the Seoul-based Asan Institute for Policy Studies found that 96 percent of South Koreans believed the U.S.–South Korean alliance would remain necessary for the foreseeable future, and 80 percent supported the continued stationing of U.S. forces in South Korea. Only 14 percent preferred China as a partner. But if the United States were to severely undermine its security guarantee, such as by weakening its stated commitments or visibly reducing its military presence, the calculations of South Korean elites, if not public sentiment, could change. And if a major ally were to abandon a 70-year-old arrangement, other U.S. allies might begin to reconsider their own relationships with Washington, too.
The United States and South Korea are no longer up against North Korea alone—a country that, for decades, was dangerous but isolated. Now, Washington and Seoul cannot deter North Korea without factoring in Russia’s willingness to sustain the regime and China’s willingness to intervene in any conflict. In 1950, the United States made the mistake of failing to signal that the Korean Peninsula mattered—and the result was a three-year war and a seven-decade armistice that has left the peninsula in a perilous standoff between nuclear-armed powers. Today, Washington can still demand greater contributions from Seoul while living up to its own security commitments. Only a strong, steadfast United States can deter Kim, Putin, and Xi from aggression that would spell disaster for Washington and its allies.
Loading…
