This week, Kyiv received a warning that threatens to alter the course of the war they've been engaged in for four years. As many as 30,000 more North Korean troops may be heading to facilities set up by Moscow in its Voronezh region, just across the border from Ukraine, says Volodymyr Zelenskyy. If he's telling the truth, it would more than double in the event of war and, maybe, triple Pyongyang's commitment to a war that was never to be played out in Europe.

It's not just a coincidence. Last week, the North Korean foreign minister, Choe Son-hui, traveled to Moscow for four days of meetings with Vladimir Putin and Sergei Lavrov, a visit that was seen as a prelude to a visit by Kim Jong-un himself. A week later, another less-anticipated development emerged and could prove to be just as significant strategically: Ukrainian military intelligence reportedly has been monitoring a second move by a North Korean missile unit into western Russia, with up to 120 ballistic missiles and six launchers targeting Ukraine. In total, the two advances signal a change from North Korea's support of Russian defenses to a more proactive role in the actual fighting of the war.

It is useful to examine the reasons for this by looking at where we've come from. The first deployment, in late 2024, of about 12,000-14,000 troops, was limited to Ukraine's Kursk region, where the country launched a surprise cross-border incursion. The Russians were shooting and dying to protect Russian territory, not Ukrainian and allowed both governments to have a fig leaf of ambiguity over the extent to which their troops had been involved in Korea. That fig leaf fell in January this year, when North Korea's ruling party publicly acknowledged Kim Jong-un's order to deploy and proclaimed the recapture of Kursk as evidence of "unbreakable wartime friendship" between the two capitals. The cost of casualties has been high. There are estimates from Ukraine and South Korea of North Korean casualties ranging from 2,000 to 2,250, and several thousand more injured, which Pyongyang has never admitted to its own people.

If Zelenskyy's side is true, the only thing about to change is geography. Since the Russians have since recovered almost all of the land they ceded at Kursk, there is no longer a Russian border area to defend for North Korean troops. Any new deployment would have to happen within the borders of Ukraine, which Pyongyang's troops have never been able to do. This is not so much to replace Russian losses in number as to provide them with a reserve force they can deploy for offensive action later this year, as both sides prepare for a bumpy autumn campaign on the battlefield, according to analysts monitoring the war.

A much larger, more significant story lies behind the soldiers: money. South Korea's central bank said North Korea's economy expanded 3.5 percent in 2025 for the third consecutive year and by the Bank of Korea's estimate, to a level higher than pre-2017 norms for the first time since the United Nations imposed sanctions in that year. The economy has rebounded to 48.5 trillion won, nominal GNI, which is still only 2 percent of South Korea's economy, but a dramatic turnaround for a decade in a decade of isolation. The central bank has attributed the turnaround entirely to the arms trades to Russia, growing business with China and state-led construction, among other areas in which the war demand has had a direct impact.

There's no way to overestimate the scale of that arms trade. The Institute for National Security Strategy at Seoul estimates that North Korea has received up to 14.4 billion dollars in military aid from Russia over about two years, based on shipments that reportedly increased from about 20,000 shipping containers of munitions in early 2025 to 33,000 by this March. That's a pretty slow rate of growth, says Bruce Bechtol, North Korea arms expert at Angelo State University, and that's why: those containers contain artillery shells, multiple-launch rocket systems, anti-tank missiles and the same short-range ballistic missiles that now are said to be advancing to the front with their own crews. For its part, Pyongyang has been said to have provided cash, food, energy shipments and more worryingly, for the region, technical assistance that experts say is helping Pyongyang advance its missile and satellite programs, but Western intelligence has been unable to confirm the extent of the technology transfer.

The sanctions system established to stop all of this is still in place. It just lost its enforcing power by two of the governments that approved it. Russia's veto at the UN Security Council has effectively crippled the monitoring system that used to keep an eye on Pyongyang's actions, and China's trade with North Korea is going on pretty much as normal. The new sanctions against individuals and shipping networks connected to the arms pipeline, most recently imposed by Britain over an arms-for-oil scheme, have been ineffective in slowing the underlying trade, which involves China, Russia, India, Pakistan, Israel and India's main regional rivals.

The ramifications of the war in Ukraine go far beyond the borders of Asia. In Zelenskyy's own, stark terms, Russia is instructing North Korea in how to fight modern, large-scale war, how to upgrade their weapons in actual combat and how to test missile systems that could someday be directed at Seoul, Tokyo or American bases in Guam. The deeper path is now clear, regardless of the number of 30,000 troops that show up. What has been a period of isolation has suddenly turned into a battlefield for training and a market for the one thing that Russia has always had plenty of, in its war of attrition.That is the forecast for North Korea's economic growth in the past three years, with 2025 being its best sustained growth period in years since the tightening of the sanctions in 2017, which the Bank of Korea directly correlates with the Russia arms pipeline described above.