KYIV, Ukraine >> For weeks, Ukrainian troops braced for an unfamiliar enemy: North Korean soldiers sent to bolster Moscow’s forces after Ukraine launched a lightning-fast incursion and seized territory in Russia’s Kursk region over the summer.

Their arrival marked a new and alarming phase in the war. And while initially inexperienced on the battlefield, North Korean troops have adapted quickly — a development that could have far-reaching consequences as they gain combat knowledge in the war against Ukraine.

Unlike the Russian troops Ukraine has been battling for nearly three years, Kyiv’s forces were uncertain about what to expect from this new adversary, drawn into the war after Moscow and Pyongyang signed an agreement pledging military assistance using “all means” if either were attacked.

One Ukrainian soldier who has witnessed North Koreans in battle described them as disciplined and highly methodical, saying they were more professional than their Russian counterparts. The soldier spoke to The Associated Press on condition of anonymity because he was not authorized to discuss the sensitive military issue.

However, other soldiers, including Ukrainian special forces, have shared battlefield drone footage on the Telegram messaging app mocking their tactics as outdated.

Nevertheless, there is consensus among Ukrainian soldiers, military intelligence and others monitoring developments on the ground: While Pyongyang’s troops lacked battlefield experience when they arrived, that has been changing quickly.

With 1.2 million troops, North Korea’s military ranks among the largest standing armies globally. But its post-Korean War foreign engagements have been limited, leaving them inexperienced with modern warfare technologies like drones.

“For the first time in decades, the North Korean army is gaining real military experience,” said Andrii Yusov, spokesperson for Ukraine’s military intelligence agency. “This is a global challenge — not just for Ukraine and Europe, but for the entire world.”

Identifying the presence of North Korean troops

Despite Ukrainian, U.S. and South Korean assertions that Pyongyang has sent 10,000-12,000 troops to fight alongside Russia in the Kursk border region, Moscow has never publicly acknowledged the North Korean forces.

While reports of their presence first emerged in October, Ukrainian troops only confirmed engagement on the ground in December.

Analysts say that without the influx of North Korean troops, Russia would have struggled to pursue its strategy of overwhelming Ukraine by throwing large numbers of soldiers into the battle for Kursk.

While Moscow’s counterattack in Kursk has inflicted thousands of Ukrainian casualties, Kyiv’s overstretched forces have managed to hold on to about half of the 984 square kilometers (380 square miles) seized in August, though the situation remains dynamic. Besides the symbolic impact of Ukraine’s success capturing Russian territory, control of Kursk could also be a bargaining chip in any ceasefire negotiations.

According to Ukraine’s intelligence agency, the North Korean soldiers are operating alongside Russian units, with the latter providing reconnaissance and electronic warfare support.

The North Koreans wear Russian military uniforms with fake military IDs in their pockets, according to a report by a Ukrainian military unit that has observed them on the battlefield, and they could easily be mistaken for Russian soldiers.

The subterfuge means Moscow and “its representatives at the U.N. can deny the facts,” said Yusov, the Ukrainian military intelligence spokesperson.

Among the things proving their presence is that they have been heard speaking Korean with North Korean accents in intercepted communications, Yusov said.

He said the North Korean troops are using their own weapons and equipment and have learned to cope with the improvised explosives-laden drones that have become emblematic of the war, first-hand experience even some NATO-member countries don’t have.

“This is a new level of threat,” Yusov said. “Regional countries must prepare for what this means in the future.”

North Koreans gain invaluable experience on the battlefield

The North Koreans’ early missteps were largely caused by inexperience, such as moving in large groups in open terrain, making them easy targets for drones and artillery strikes.

According to the Ukrainian military unit’s report, the North Korean soldiers were spotted easily as they moved in single-file columns through forest in groups of three, with 3 to 5 meters (yards) between soldiers. On open terrain, they moved in dispersed formations of five to 15 soldiers, making them vulnerable and leading to heavy losses.

However, during night operations, their movements were swift and units oriented themselves using red flashlights along routes, the report said.

“They’re fast, physically well-prepared, and act strictly according to their algorithms,” said the Ukrainian soldier who spoke to the AP. “If you drill the same routines for years, to the point where they can be executed blindfolded, it will yield results.”

Despite their discipline, their lack of combat experience hindered their effectiveness. The Ukrainian military reported that North Korean troops often sustained heavy losses, with many killed by drones.

On Thursday, Ukrainian President Volodymyr Zelenskyy put the number of killed or wounded North Koreans at 4,000, though U.S. estimates are lower, at around 1,200.

“Much of their military doctrine and training is based on strategies and experiences from over half a century ago,” said Glib Voloskyi, a military analyst with the Ukrainian think tank CBA Initiatives Center.

The large-group formations date to when artillery accuracy was significantly lower, and observing troop movements much more difficult. Today, reconnaissance and so-called first-person view drones, or FPVs, that transmit video allowing soldiers to strike targets in real time have made the battlefield highly transparent, and anyone stepping onto it without cover, let alone moving in groups, is immediately spotted.

“But it is only a matter of time before they acquire the necessary skills to improve their combat effectiveness, which, combined with their discipline and training, could make them a significant military force,” Voloskyi said.